Liquid desiccant regeneration system, systems including the same, and methods of operating the same

ABSTRACT

A liquid desiccant regeneration system and method of liquid desiccant regeneration are described. The liquid desiccant regeneration system includes a liquid desiccant regenerator having an engine producing a heated exit stream, and at least one dehydrating tube comprising a first water vapor permeable wall. A low concentration liquid desiccant stream feeds into the liquid desiccant regenerator, while a high concentration liquid desiccant stream exiting the liquid desiccant regenerator. A carrier stream and the low concentration liquid desiccant are in contact with opposite sides of the first water vapor permeable wall, and the low concentration liquid desiccant stream is heated by heat from the heated exit stream to drive water from the low concentration liquid desiccant stream through the first water vapor permeable wall to the carrier stream to form a humidified carrier stream. As a result, the desiccant concentration in the high concentration liquid desiccant stream is higher than a desiccant concentration in the low concentration liquid desiccant stream.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.14/623,881, filed Feb. 17, 2015, Provisional Patent Application No.61/940,455, filed Feb. 16, 2014; U.S. Provisional Patent Application No.61/949,893, filed Mar. 7, 2014; U.S. Provisional Patent Application No.61/991,198, filed May 9, 2014; U.S. Provisional Patent Application No.62/058,476, filed Oct. 1, 2014; and U.S. Provisional Patent ApplicationNo. 62/058,479, filed Oct. 1, 2014, the entireties of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of liquid desiccantregeneration systems, such as liquid desiccant air conditioning systems.

BACKGROUND

Air conditioning refers to the heating, cooling, cleaning,humidification and dehumidification of air. The most prevalent airconditioning systems employ vapor compression cycles, in which heat ispumped from one environment to another via a refrigerant that operatesunder two different pressure regimes so that the temperature can beincreased when heat needs to be rejected to the environment or decreasedwhen heat is to be absorbed by the refrigerant. The pressure differencein these systems is maintained by means of a mechanical compressor. Thiscompressor is powered using electricity. The vast majority of airconditioning systems in commercial use employ the vapor compressioncycle.

The principal limitation to the vapor compression cycle is that it isfor all intents and purposes a sensible heat rejection device with minorcapabilities to address the latent heat needs of a building This isbecause the vapor compression cycle is only able to change thetemperature of the air. Given this, the prevalent manner in which vaporcompression air conditioning systems address the latent heat of abuilding is by reducing the temperature of the air to a point below itsdew point and by removing water through condensation. In most cases, theair must be reheated in order to arrive at the desired building supplyair temperature. This process is energy intensive.

Methods for dehumidification of the air conditioning incoming air havebeen invented and proposed. Among these is the use of a liquid desiccantloop coupled with an evaporative cooling system to generate cooling anddehumidification without requiring cooling the air to the dew point.These systems are designed using a plate heat and mass transferarrangement in which liquid desiccant flows within selectively waterpermeable membranes that are attached to flat plates. The liquiddesiccant flow absorbs moisture from air being dehumidified and thentransfers it to a separate air stream that absorbs this moisture fromthe liquid desiccant. The air being dehumidified drops in temperature,cooling the air being dehumidified. Multiple plates stacked togetherform the heat and mass transfer device.

The plate arrangement has advantages in that it allows for a singledevice that does both air cooling and dehumidification using liquiddesiccant streams. An example of this is described in US PatentApplication, US 20100319370A1, titled “Indirect evaporative cooler usingmembrane-contained liquid desiccant for dehumidification.”

SUMMARY

In one embodiment, a liquid desiccant regeneration system is described.The desiccant regeneration system can include a liquid desiccantregenerator, a low concentration liquid desiccant stream feeding intothe liquid desiccant regenerator, and a high concentration liquiddesiccant stream exiting the liquid desiccant regenerator. The liquiddesiccant regenerator can include an engine producing a heated exitstream, and at least one dehydrating tube comprising a first water vaporpermeable wall. A carrier stream and the low concentration liquiddesiccant are in contact with opposite sides of the first water vaporpermeable wall and the low concentration liquid desiccant stream isheated by heat from the heated exit stream to drive water from the lowconcentration liquid desiccant stream through the first water vaporpermeable wall to the carrier stream to form a humidified carrierstream. The desiccant concentration in the high concentration liquiddesiccant stream is higher than a desiccant concentration in the lowconcentration liquid desiccant stream.

A method of operating liquid desiccant regenerating systems such asthose described herein is also provided. In some embodiments, the methodcan include providing a low concentration liquid desiccant stream;providing a liquid desiccant regenerator; and operating the liquiddesiccant regenerating system to produce the high concentration liquiddesiccant stream, which has a higher desiccant concentration than thelow concentration liquid desiccant stream. The liquid desiccantregenerator 12 can include an engine, wherein heat from the engine isused to convert the low concentration liquid desiccant stream to thehigh concentration liquid desiccant stream.

These and other features, objects and advantages of the presentinvention will become more apparent to one skilled in the art from thefollowing description and claims when read in light of the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a liquid desiccant regeneration system asdescribed herein.

FIG. 2 is a diagram of another liquid desiccant regeneration system asdescribed herein.

FIG. 3A is a diagram of a heat and mass exchange system that can be usedfor dehumidification, while FIG. 3B shows a heat and mass exchangesystem that can be used for cooling and dehumidification.

FIG. 4 shows a diagram of a combined liquid desiccant regenerator andwater recovery system.

FIG. 5 shows one shell and tube heat and mass exchange system that canbe used for cooling and dehumidification.

FIG. 6 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 7 is a diagram of a dehumidifier as described herein.

FIG. 8 is a diagram of a portion of a water recovery stage as describedherein.

FIG. 9 is a diagram of a portion of an evaporative cooling stage asdescribed herein.

FIG. 10 is a diagram showing a liquid desiccant handling system for anevaporative cooling and dehumidification stage according to anembodiment described herein.

FIG. 11A is a side view of an arrangement of conduits that can be usedin mass or heat transfer processed described herein, while FIG. 11B is afront view of the arrangement of FIG. 11A.

FIG. 12 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 13 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 14 is a perspective view of an arrangement of conduits as describedherein.

FIG. 15 is a side view of a dehumidification chamber as describedherein.

FIG. 16 is a top view of the dehumidification chamber of FIG. 15.

FIG. 17 is a top view of an air dehumidifier with a liquid desiccantcooling system as described herein.

FIG. 18 is a diagram showing a liquid desiccant handling system for anevaporative cooling and dehumidification stage according to anembodiment described herein.

FIG. 19A is a perspective view of a heat and mass transfer device asdescribed herein, while FIG. 19B is a cross-sectional view of the heatand mass transfer device of FIG. 19A.

FIG. 20 is a perspective view of a tube-in-tube heat and mass transferdevice as described herein.

FIG. 21 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 22 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 23 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 24 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 25 is a cross-sectional view of a mass transfer conduit asdescribed herein.

FIG. 26 is a perspective view of multiple filtration conduits housed ina larger cylindrical vessel for removal of solids from water at elevatedpressures.

FIG. 27 is a perspective view of a porous support material that can beused for forming a mass support conduit.

FIG. 28 is a perspective, semi-transparent view of an air conditioningprocess using two heat and mass exchange stages, which may be separateunits or a single, combined unit.

FIG. 29 is a perspective, semi-transparent view of an air conditioningprocess using two heat and mass exchange stages, which may be separateunits or a single, combined unit.

FIG. 30 is a perspective, semi-transparent view of an air conditioningprocess using two heat and mass exchange stages, which may be separateunits or a single, combined unit.

FIG. 31 is a perspective, semi-transparent view of an air conditioningprocess using two heat and mass exchange stages, which may be separateunits or a single, combined unit.

FIG. 32 is a diagram of a liquid desiccant regeneration anddehumidification system as described herein.

FIG. 33 is a diagram of a misting device as disclosed herein.

FIG. 34 is a diagram of a liquid desiccant regeneration system asdescribed herein.

FIG. 35 is a diagram of a liquid desiccant regeneration system asdescribed herein.

FIG. 36 is a perspective view of a heat and mass exchange stage asdescribed herein.

FIG. 37 is a perspective view of a heat and mass exchange stage asdescribed herein.

FIG. 38 is a cross-sectional view showing the flow pattern of fluidthrough a heat and mass exchange stage as described herein.

FIG. 39 is a cross-sectional view of a tube-in-tube assembly asdescribed herein.

FIG. 40 is a cross-sectional view of a tube-in-tube assembly asdescribed herein.

FIG. 41 is a cross-sectional view of a tube-in-tube assembly asdescribed herein.

FIG. 42A is a side or top view of a heat and mass exchange assembly,including flow disruptors, as described herein, while FIG. 42B is a topor side view of the same heat and mass exchange assembly.

FIG. 43 is a side or top view of a heat and mass exchange assembly,including flow disruptors, as described herein.

DETAILED DESCRIPTION

As shown in FIGS. 1-43, a liquid desiccant regeneration system isdisclosed. The system utilizes a heated exit stream (e.g., exhaust,heated heat exchange fluid, etc.) from an engine to regenerate lowconcentration liquid desiccant. In one example, the low concentrationliquid desiccant can be the exit stream of a liquid desiccant airconditioning system that uses high concentration liquid desiccant todehumidify air. Water from the liquid desiccant regeneration system canalso be recovered and used, for example, to provide evaporative coolingto the air conditioning system. Power generated by the engine is used topower the air conditioner, the building being cooled and, where excesspower is produced, the power can be sold back to the power grid orstored for future use (e.g., in batteries, capacitors, etc.).

As shown in FIG. 1, a liquid desiccant regeneration system 10 isdescribed. The desiccant regeneration system 10 can include a liquiddesiccant regenerator 12, a low concentration liquid desiccant stream 14feeding into the liquid desiccant regenerator 12, and a highconcentration liquid desiccant stream 16 exiting the liquid desiccantregenerator 12. The liquid desiccant regenerator 12 can include anengine 18 producing a heated exit stream 20, and at least onedehydrating conduit 22 comprising a first water vapor permeable wall 24.As shown in FIG. 1, a carrier stream 26 and the low concentration liquiddesiccant 14 are in contact with opposite sides of the first water vaporpermeable wall 24 and the low concentration liquid desiccant stream 14is heated by heat from the heated exit stream 20 to drive water from thelow concentration liquid desiccant stream 14 through the first watervapor permeable wall 24 to the carrier stream 26 to form a humidifiedcarrier stream 28. The desiccant concentration in the high concentrationliquid desiccant stream 16 is higher than a desiccant concentration inthe low concentration liquid desiccant stream 14.

As will become apparent, while FIG. 1 shows a generalized embodiment ofthe liquid desiccant regeneration system 10, FIGS. 2, 6, 12, 13, 21, 22,23, 24, 32, 34, and 35 show a variety of other embodiments having thesame or similar features. For example, FIGS. 2, 6, 12, and 13schematically show liquid desiccant regeneration systems 10 that useseparate heat exchangers and mass exchangers, while FIGS. 21, 22, 23,24, 32, 34, and 35 schematically show similar systems 10 employingcombined heat and mass exchangers. As will be understood, depending ofthe application and objectives, a desiccant regeneration system 10 canemploy individual heat exchangers and mass exchangers, combined heat andmass exchangers, or a combination of both. Additional details on heatand mass exchangers useful in the desiccant regeneration systems 10described herein can be found in U.S. patent application Ser. No.14/623,797, entitled “Heat and Mass Transfer Device and SystemsIncluding the Same,” by Daniel A. Betts and Matthew Daniel Graham, filedFeb. 17, 2015, the entirety of which is incorporated herein byreference.

In some embodiments, the heated exit stream 20 is selected from thegroup consisting of heated heat exchange fluid, an exhaust stream, orboth. For example, the heated heat exchange fluid can be coolant used tokeep the engine 18 from overheating. In some such embodiments, such asthose shown in FIGS. 1, 2, 6, 12, 13, 21, 22, 23, 24, 32, 34, and 35,the heated heat exchange fluid 21 a can pass through the liquiddesiccant regenerator 12 as part of a closed loop circuit with theengine 18.

In some embodiments, the heated exit stream 20 can be an exhaust stream,such as the gaseous exhaust stream 21 b from an internal combustionengine or the gaseous exhaust stream 21 b from the anode or cathodechamber of a fuel cell.

In some embodiments, the heated exit stream 20 is an exhaust stream 21 band the carrier stream 26 comprises the exhaust stream 21 b. In otherembodiments, such as those shown in FIGS. 1, 34, and 35, the liquiddesiccant regenerator 12 further comprises a heat exchanger 30, whereinthe heated exit stream 20 contacts and heats the carrier stream 26 inthe heat exchanger 30. In some such embodiments, the carrier stream 26includes ambient air, recirculated air from a space being airconditioned, or a combination of both. Such a configuration can bebeneficial in that these sources of the carrier stream 26 generally havea lower humidity than the heated exhaust stream 20, 21 b, so that thedriving force to regenerate the low concentration liquid desiccant 14 isincreased.

In some embodiments, the heated exit stream 20 is heated heat exchangeliquid 21 a exiting the engine 18, and the heated heat exchange liquid21 a contacts and heats the low concentration liquid desiccant stream14, the carrier stream 26, or both.

In some embodiments, such as FIG. 1, the heated exit stream 20 includesboth a heated heat exchange liquid 21 a exiting the engine and a heatedexhaust stream 21 b. In such embodiments, the heated heat exchangeliquid 21 a contacts and heats the low concentration liquid desiccant14, and (a) the heated exhaust stream 21 b contacts and heats thecarrier stream 26, or (b) the carrier stream 26 comprises the heatedexhaust stream 21 b.

In some embodiments, the high concentration liquid desiccant stream 16is directed through an air conditioning system 32. In some embodiments,the air conditioning system 32 includes at least one dehumidificationconduit 34 that has a second water vapor permeable wall 36. In someembodiments, a process air stream 38 and the high concentration liquiddesiccant stream 16 are in contact with opposite sides of the secondwater vapor permeable wall 36, and moisture from the process air stream38 passes through the second water vapor permeable wall 36 to the highconcentration liquid desiccant stream 16, thereby dehumidifying theprocess air stream 38 and diluting the high concentration liquiddesiccant stream 16.

In some embodiments, the air conditioning system 32 also includes atleast one air conditioning heat exchange conduit 40, where (a) the highconcentration liquid desiccant stream 16 and a heat exchange fluid 42are in contact with opposite sides of the air conditioning heat exchangeconduits 40, for cooling the high concentration liquid desiccant stream16, as shown in FIGS. 1, 6, 12, 13, 21, 22, 23, and 32; (b) the processair stream 38 and a heat exchange fluid 42 are in contact with oppositesides of the air conditioning heat exchange conduits 40, for cooling theprocess air stream 38, as shown in FIG. 21 (process air 2006, heatexchange fluid 2009), 22, 23, and 32; or (c) the high concentrationliquid desiccant stream 16 and a first heat exchange fluid 42 a are incontact with opposite sides of a first group of the air conditioningheat exchange conduits 40 a, for cooling the high concentration liquiddesiccant stream 16, and the process air stream 38 and a second heatexchange fluid 42 b are in contact with opposite sides of a second groupof the air conditioning heat exchange conduits 40 b, for cooling saidprocess air, as shown in FIGS. 21, 22, 23, and 32.

As one example, in the system of FIG. 21, the liquid desiccant streamentering the HMX at 2118A can contact the first heat exchange fluid 42a/2003, i.e. , air, where the air 2003 is on the inside of atube-in-tube component and the liquid desiccant stream is on the outsideof that tube-in-tube component. The process air stream 38/2006 can thencontact the second heat exchange fluid 42 b (either water 2008 or air2009) as the process air stream 38/2006 passes through the next HMX.Additional details about these configurations can be found in thediscussion of the systems of FIGS. 21, 22, 23, and 32.

The heat exchange fluids 42 a, 42 b used herein include, but are notlimited to, chilled water or other coolants, including a combination ofair and water, which may be used in a heat exchanger or which may besprayed in a space or coated on a surface to provide psychrometriccooling. For example, FIG. 1 shows an embodiment where a water recoverysystem 44 supplies a water stream 46 that is sprayed in order to coolthe high concentration liquid desiccant stream 16 as it flows within thedehumidification conduit(s) 34.

In some embodiments, the liquid desiccant regeneration system 10 alsoincludes a water recovery system 44. The water recovery system 44 caninclude a water recovery heat exchange conduit 48, where the humidifiedcarrier air 28 and a water recovery heat transfer fluid 50 are incontact with opposite sides of the water recovery heat exchange conduits48. An outlet of the water recovery heat exchanger 52 can be in fluidcommunication with a water reservoir 54 for storing water precipitatingfrom the humidified carrier air 28. In some embodiments, the waterrecovery system 44 includes a flow control system 56 for controllingtransport of water from the water reservoir 54 to one side of the airconditioning heat exchange conduits 40. The flow control system 56 caninclude a controller 58 and a flow control device 60. Examples of flowcontrol devices 60 include, but are not limited to, pumps and valves.

In some embodiments, the desiccant regeneration system 10 includes ahigh concentration liquid desiccant reservoir 62, having an inlet influid communication with an outlet of the liquid desiccant regenerator12 and an outlet in fluid communication with an inlet of the airconditioning system 32. In some embodiments, the desiccant regenerationsystem 10 includes a low concentration liquid desiccant reservoir 64,having an inlet in fluid communication with an outlet of the airconditioning system 32 and an outlet in fluid communication with aninlet of the liquid desiccant regenerator 12.

In some embodiments, the capacity of the high concentration liquiddesiccant reservoir 62 is sufficient to operate the air conditioningsystem 32 solely from the high concentration liquid desiccant reservoir62 continuously for at least one hour, or at least two hours, or atleast four hours, or at least eight hours. In some embodiments, thecapacity of the low concentration liquid desiccant reservoir 64 issufficient to operate the liquid desiccant regenerator continuously fromthe low concentration liquid desiccant reservoir 64 for at least onehour, or at least two hours, or at least four hours, or at least eighthours.

The liquid desiccant regeneration systems 10 described herein includeengines 18 that are adapted for generating energy from a fuel source 66.Thus, in some embodiments, it will be desirable to operate the liquiddesiccant regenerator 12, which also produces an electricity stream 68,even when the air conditioning system 32 is not operating.

In some embodiments, the fuel source 66 is a fuel tank or a fuel lineproviding fuel from a municipal source or other source. Examples of fuelsources 66 include, but are not limited to, natural gas, propane,butane, liquefied petroleum gas (LPG), hydrogen, city gas (i.e., gaspiped to the building from a municipality or other source), andcombinations thereof. In some embodiments, the fuel source 66 will bepre-processed before being introduced into the engine 18. For example, afuel processor can convert natural gas into a hydrogen rich gas beforeit is fed into a fuel cell engine 18.

In some embodiments, the air conditioning system 32 consumes highconcentration liquid desiccant at the same rate that the liquiddesiccant regenerator 12 regenerates the low concentration liquiddesiccant 14 into a high concentration liquid desiccant 16. Because ofthe desire to operate these two systems 12, 32 independently from oneanother, in some embodiments, the air conditioning system 32 can consumehigh concentration liquid desiccant 16 at a faster or slower rate thanthe liquid desiccant regenerator 12 regenerates the low concentrationliquid desiccant 14 into high concentration liquid desiccant 16. In someembodiments, the consumption of high concentration liquid desiccant 16by the air conditioning system 32 is at least 10% faster or at least 10%slower than regeneration of the low concentration liquid desiccant 14 bythe liquid desiccant regenerator 12. In some embodiments, theconsumption of high concentration liquid desiccant 16 by the airconditioning system 32 is at least 20% faster or at least 20% slowerthan regeneration of the low concentration liquid desiccant 14 into highconcentration liquid desiccant 16 by the liquid desiccant regenerator12. In some embodiments, the consumption of high concentration liquiddesiccant 16 by the air conditioning system 32 is variable. In someembodiments, the regeneration of the low concentration liquid desiccant14 into high concentration liquid desiccant 16 by the liquid desiccantregenerator 12 is variable.

In some embodiments, the engine 18 generates electricity 68 throughelectrochemical oxidation of a fuel 66. Examples of engines 18 capableof generating electricity 68 through electrochemical oxidation of a fuelinclude, but are not limited to, low and high temperature protonexchange membrane fuel cells, solid oxide fuel cells, and flowbatteries.

The electricity 68 produced by the engine 18 can be provided to anexternal power grid, such as the building being air conditioned, thelocal power grid (e.g., municipal power grid), or both. In someembodiments, electricity 68 produced by the engine 18 is supplied to theair conditioning system 32 or any other electrical components (e.g.,pumps, processors, valves, etc.) of the desiccant regeneration system10.

In some embodiments, the liquid desiccant concentration in the highconcentration liquid desiccant stream 16 can be at least 0.5 wt-% higherthan the liquid desiccant concentration in the low concentration liquiddesiccant stream 14. In some embodiments, the difference inconcentration can be at least at least 1 wt-% higher, at least 1.5 wt-%higher, at least 2 wt/% higher, at least 2.5 wt-% higher, at least 3wt-% higher, at least 3.5 wt-% higher, or at least 4 wt-% higher in thehigh concentration liquid desiccant stream 16 than in the lowconcentration liquid desiccant stream 14.

The liquid desiccant can be composed of any hygroscopic liquid such asaqueous salt solutions (e.g., LiCl, NaCl, CaCl₂), alcohol solutions(e.g. Glycerol, methanol, ethanol), or aqueous chemical agents (e.g.CaSO₄). All materials wetted with the liquid desiccant are constructedof materials that are chemically compatible with the liquid desiccant.

In some embodiments, the liquid desiccant concentration in the lowconcentration liquid desiccant stream (14) is at least 10 wt-%, at least20 wt-%, at least 25 wt-%, at least 30 wt-%, at least 33 wt-%, at least34 wt-%, at least 35 wt-%, at least 36 wt-%, at least 37 wt-%, at least38 wt-%, or at least 39 wt-%. In some embodiments, the liquid desiccantconcentration in the low concentration liquid desiccant stream (14) is50 wt-% or less, 45 wt-% or less, 40 wt-% or less, 39 wt-% or less, 38wt-% or less, 37 wt-% or less, 36 wt-% or less, or 37 wt-% or less.

In some embodiments, the liquid desiccant concentration in the highconcentration liquid desiccant stream (16) is at least 20 wt-%, at least25 wt-%, at least 30 wt-%, at least 34 wt-%, at least 35 wt-%, at least36 wt-%, at least 37 wt-%, at least 38 wt-%, at least 39 wt-%, or atleast 40 wt-%. In some embodiments, the liquid desiccant concentrationin the high concentration liquid desiccant stream (16) is 50 wt-% orless, 45 wt-% or less, 44 wt-% or less, 43 wt-% or less, 42 wt-% orless, 41 wt-% or less, 40 wt-% or less, 39 wt-% or less, 38 wt-% orless, or 37 wt-% or less.

Because liquid desiccants can be corrosive, the duct-work or pipingcoming into contact with the liquid desiccant streams 14, 16 can becorrosion resistant. For example, the duct-work or piping can be formedfrom corrosion resistant materials or the inside or outside of theduct-work or piping can be coated with corrosion resistant materials.Examples of materials that are corrosion resistant to liquid desiccantsinclude, but are not limited to ehylene propylene diene rubber (EPDM),fluorine rubber (FKM), nitrile rubber (NBR), perfluorinated elastomers(FFKM), polytetrafluoethylene (PTFE), rigid polyvinyl chloride (PVC),polyolefin materials, such as polypropylene (PP), polyethylene (PE),high density polyethelene (HDPE), and others, polyvinylidene fluoride(PVDF), polyphenylene sulfide (PPS), poly ether ether ketone (PEEK), andchroroprene rubber (CR), sulfonated tetrafluoroethylene basedfluoropolymer-copolymer (such as Nation, which is sold by DuPont), waterconducting fluoropolymers, and non-fluorinated proton conductingpolymers.

As used herein, the phrases water vapor permeable and micro-porous areused interchangeably. Where a conduit wall, membrane, or material iswater vapor permeable or micro-porous, the structure can be made of amaterial that is hydrophobic, and impermeable to liquids but permeableto water vapor. Such water vapor permeable materials are also referredto as mass transfer conduits, tubes or materials. Examples of solid ormonolithic, water vapor permeable materials include sulfonatedtetrafluoroethylene based fluoropolymer-copolymer (e.g., Nafion™, soldby DuPont), water conducting fluoropolymers, and non-fluorinated protonconducting polymers (e.g., NanoClear™, sold by Dais Analytic), and highdensity polyethelene (HDPE).

In some embodiments, the water vapor permeable materials are formed fromfibers of hydrophobic materials. Examples include spunbond or meltblownpolymer materials. Such water vapor permeable materials are generallyformed from hydrophobic materials. As used herein “hydrophobic” refersto materials with a contact angle of greater than 90° (e.g., at least100°, at least 115°, at least 120°, or at least)135°.

A method of operating liquid desiccant regenerating systems 10 such asthose described herein is also provided. In some embodiments, the methodcan include providing a low concentration liquid desiccant stream 14;providing a liquid desiccant regenerator 12, and operating the liquiddesiccant regenerating system 10 to produce the high concentrationliquid desiccant stream 16, which has a higher desiccant concentrationthan the low concentration liquid desiccant stream 14. The liquiddesiccant regenerator 12 can include an engine 18, wherein heat from theengine 18 is used to convert the low concentration liquid desiccantstream 14 to the high concentration liquid desiccant stream 16.

In some embodiments, the liquid desiccant regeneration system 10 alsoincludes an air conditioning system 32 that converts the highconcentration liquid desiccant stream 16 to a low concentration liquiddesiccant stream 14 while dehumidifying process air 38 supplied to anair conditioned space. In some embodiments, the operating step includestransporting the high concentration liquid desiccant stream 16 to theair conditioning system 32, then transporting the low concentrationliquid desiccant stream 14 from the air conditioning system 32 to theliquid desiccant regenerating system 12. In some embodiments, the liquiddesiccant flows in a closed loop.

In some embodiments, the operating step comprises operating the liquiddesiccant regenerator 12 continuously, and operating the airconditioning system 32 intermittently. In some embodiments, the airconditioning system 32 operates when a temperature, a humidity, or bothof the space being air conditioned passes a target temperature orhumidity, and the air conditioning system 32 does not operate when atemperature, a humidity, or both of the space being air conditioned areon the other side of the target temperature or humidity.

In some embodiments, the operating step includes operating the liquiddesiccant regenerator 12 when the air conditioning system 32 is notoperating. For example, the liquid desiccant regenerator 12 can operateduring particular times of the day, such as when there is a peak demandfor electricity, regardless of whether the air conditioning system 32 isoperating.

In some embodiments, the operating step includes operating the airconditioning system 32 when the liquid desiccant regenerator 12 is notoperating. For example, if there is an excess of high concentrationliquid desiccant in the high concentration liquid desiccant reservoir62, the air conditioning system 32 can be operated without the liquiddesiccant regenerator 12 in order to correct this imbalance.Alternatively, if the high concentration liquid desiccant reservoir 62has excess high concentration liquid desiccant 16 and the airconditioned space does not require air conditioning, then this excesshigh concentration liquid desiccant 16 could be used to capture waterfrom a process air stream 38, such as outside air, where thedehumidified process air 38 is exhausted and not introduced into thebuilding. The water captured from the process air 38 can then berecovered using a water recovery system 44 and stored in the water tank54.

Many applications for the system 10 described herein have a mismatchbetween electricity need and air conditioning needs. For example, inmost buildings, air conditioners do not operate continuously, however,the electricity load is continuous. This mismatch can be exploited toincrease the overall efficiency of the system and to potentiallydecrease its cost. Continuous operation of the engine (e.g., fuel cell)to address building load enables continuous regeneration of liquiddesiccant and continuous recovery of water even when the airconditioning system is not being utilized. Additionally, this enablescontinuous storage of water from the atmosphere and from the engine(e.g., fuel cell). The water and desiccant can be stored in the highconcentration liquid desiccant reservoir 62 and the water reservoir 54for use when air conditioning is required. The water stored can be usedto further increase the overall efficiency of the system by reducing theelectrical energy required to achieve air-cooling and air conditioning.

The stored regenerated high concentration liquid desiccant can also beused to boost the air conditioning effect by flowing greater amounts ofhigh concentration liquid desiccant than can be regenerated with thefuel cell system under steady state operation. Since air-conditioningload varies in intensity throughout the day (mid-day is hotter than inafternoons, mornings and nights), the capacity to temporarily boost airconditioning capacity is an important element in providing comfortwithout oversizing the engine 18 (e.g., fuel cell) and the airconditioning system 32.

The system 10 can also include an energy management subsystem 70composed of an engine (e.g., fuel cell) load controller, a DC to DCconverter, and a DC to AC converter. The engine load controller is ableto determine the electrical power generated by the engine (e.g., fuelcell stack). This can be done by controlling current draw from theengine and supplied to the DC to DC converter and to the DC to ACconverter. For most applications, the energy management subsystem willbe connected to the electrical grid and will be able to manage andadjust the ratio of grid power and engine 18 (e.g., fuel cell) powerused to cover the electrical load of the air conditioning system, thebuilding, and/or external source.

The energy management subsystem 70 has a role to play in takingadvantage of the mismatch between air conditioning load and electricityload throughout the day. As current draw from the engine 18 (e.g., fuelcell) is decreased, the efficiency of the engine increases, resulting indecrease in fuel consumed. However, as efficiency increases, heat andwater production also decreases. Decreased heat results in decreasedrate of liquid desiccant regeneration by the liquid desiccantregenerator 12. The opposite is also true, as current increases theengine 18 (e.g. fuel cell) heat production and water productionincreases. Because the energy management subsystem 70 controls thecurrent from the engine 18(e.g., fuel cell) it also regulates the rateof desiccant regeneration, the concentration of the regenerateddesiccant (i.e., high concentration liquid desiccant), and the capacityto take advantage of evaporative cooling in the air conditioning system32 using water from the water recovery system 44. Therefore, the energymanagement subsystem 70 controls the operations of the system throughits control software.

One distinct advantage of the described system over conventional stateof the art air conditioning systems is that the system does not consumeexternal electricity to create cooling and can be designed to produceexcess electricity, which enables the powering of additionalelectrically driven devices. Moreover, the system and method conceivespartial decoupling of the electricity production from theair-conditioning effect. This decoupling is particularly beneficialbecause air conditioning is not generally required continuously, whilethe electrical load is. These advantages enable the installation ofthese liquid desiccant regeneration air conditioning system 10 in areaswhere electricity cost is high, or where electricity service isunreliable or insufficient.

In some embodiments, excess electricity 68 produced by the engine 18 issupplied to an external power grid, such as the building being airconditioned, the local power grid (e.g., municipal power grid), or both.In some embodiments, the engine 18 generates electricity throughelectrochemical oxidation of a fuel. In some embodiments, the engine isa fuel cell. In some embodiments, electricity produced by the engine 18is supplied to the air conditioning system 32.

While the following discussion is equally applicable to all of theembodiments described herein, the systems of FIGS. 2 & 34 are discussedas examples. As shown in FIG. 2, high concentration liquid desiccantaccumulation occurs when electrochemical oxidation occurs between theanode (212) and cathode (213) of the fuel cell, thus generating heat. Inthe embodiment of FIG. 2, the heat produced by the fuel cell (18) iscaptured by coolant passing through the fuel cell cooling plate (214).Low concentration liquid desiccant (227) is introduced in the desiccantregenerator (216) by operating the liquid desiccant pump (224). The rateof liquid desiccant regeneration can be varied by varying the flow ofcoolant into the desiccant regenerator (216) and the flow of lowconcentration liquid desiccant. Water produced in the fuel cell cathode(213) and the water removed by the liquid desiccant is recovered in thewater recovery system (217). Water is accumulated in the water container(218) and high concentration liquid desiccant is accumulated in the highconcentration liquid desiccant container (221). When accumulating highconcentration liquid desiccant, the high concentration liquid desiccantpump (223) does not operate or operates at a rate that it conveys highconcentration liquid desiccant at a rate lower than the rate at which itflows into the high concentration liquid desiccant container (221). Inthis way, the thermal energy produced by the fuel cell (18) is stored,enabling a decoupling of the fuel cell electrical power output from thecooling capacity of the air conditioning subsystem (32).

Alternatively, the air conditioner (32) can operate at a higher coolingcapacity than normal when the heat of the fuel cell (18) is dissipated.This is done by using the high concentration liquid desiccant pump (223)to feed the liquid desiccant in the high concentration liquid desiccantcontainer (221) to the air conditioning dehumidifier (220) at a higherflow rate than the flow rate of high concentration liquid desiccant(226) leaving the water recovery system (217). In this case, lowconcentration liquid desiccant is accumulated in the low concentrationliquid desiccant container (219).

This type of approach is also applicable to the system shown in FIG. 34.As will be understood, while FIG. 34 focuses on liquid desiccantregeneration, high concentration liquid desiccant from the highconcentration liquid desiccant reservoir (3004, 62) could be directed toa liquid desiccant air conditioning system with the used resulting lowconcentration liquid desiccant being fed into the low concentrationliquid desiccant reservoir (3001/64). As shown in FIG. 34, the systemenables partial decoupling of engine power generation (68)with liquiddesiccant enhanced evaporative cooling (air conditioning 32). In thisembodiment, electricity generation (68) from the engine (3005) cancontinue whether the air conditioning process is operating or suspended.The heat generated (3006, 3013) by the engine (3005) is stored in theform of high concentration liquid desiccant, which is stored in the highconcentration liquid desiccant reservoir (3004, 64). The process ofoperating the engine (3005, 18) and of liquid desiccant regenerationproduces water, which is stored in a water reservoir (3020, 54). Becausewater is used to cool air through evaporative cooling, the storage ofwater is another form of storing the heat energy produced by the engine(3005).

The liquid desiccant regeneration rate can be controlled by changing theengine's (3005, 18) rate of electricity generation (68), and/or rate ofheat generation (3006, 3013). The rate of liquid desiccant regenerationcan also be varied by changing the flow rate of low concentration liquiddesiccant (3002, 14) into the HMX (3015). The concentration of highconcentration liquid desiccant can also be varied by either changing thetemperature of the hot coolant (3006) flowing into the HMX (3015). Thehot coolant (3006) temperature can be increased by reducing its flowrate while maintaining the engine (3005) operating at a constant heatoutput. Higher hot coolant (3006) temperature results in higher liquiddesiccant concentrations. Alternatively or concurrently, theconcentration of the high concentration liquid desiccant (3003, 16) canbe changed by changing the flow rate or temperature of the warm carrierair (3009).

Water recovery rate can also be changed by varying carrier air (3010)humidity, temperature and flow rate, as well as, engine exhaust (3013)temperature and flow rate. Water recovery rates can also be varied bychanging outside air (3018) flow rate through the condenser (3017). Theoptimization of these variables is executed by an energy managementsystem (3070/70). The energy management system (3070/70) can be incommunication with the various pumps, controls, engines, etc., thatcomprise the overall liquid desiccant regeneration and liquid desiccantconsumption (e.g., liquid desiccant air conditioner) system.

The stored water and high concentration liquid desiccant can be used todrive desiccant enhanced evaporative cooling air conditioning system(32). The energy management system can therefore optimize engineelectricity production, concentration of high concentration liquiddesiccant, rate of high concentration liquid desiccant storage, and rateof water recovery, based on optimization of the economic benefit of thesystem to the user on a daily or hourly basis. Thus, an energymanagement subsystem (70) can be present in any or all of the systemsdescribed herein.

The decoupling of the desiccant regenerator 12 and the air conditioningsystem 32 can be particularly beneficial because air humidity generallyrises at night as temperature drops. This makes the conditions ideal forrecovery of water while using the high concentration liquid desiccantprincipally to dehumidify air. During the middle of the day, temperaturetends to rise but humidity drops. This means that the system could beoptimized to provide greater cooling during the day using water storedduring the evening when higher relative humidity conditions exist. Theoptimization by the energy management system (3070/70) can be based onactual or anticipated sensible and latent head load in the buildingcombined with actual and anticipated outside air humidity andtemperature.

The following provides a variety of embodiments of a liquid desiccantregeneration system as described herein. Although discussed in differentgroups, it should be understood that each is consistent with the spiritof the disclosure and various unit operations from one embodiment can beexchanged with, added to, or taken from another embodiment.

As used herein, “conduit” and “duct” each have their standard meaningsand include hollow solids, including pipes, tubes, conduits, rectangularsolids, and other structures that a fluid can flow through.

As used herein, “contact” has its standard meaning and includes wherematerials within different ducts are in thermal or fluid communicationthrough a common wall or membrane. For example, two ducts would be incontact where they contain fluids on opposite sides of a micro-porousmembrane or where they contain fluids on opposite sides of athermally-conductive, impermeable wall (e.g., a metal wall).

As used herein, “fluid communication” includes connected as part of thefluid flow of the system. When used generally, fluid communicationrelates to either a direct fluid connection where two points aredirectly connected by ducts, pipes, conduits, or tubes, and indirectfluid communication where two points are separated by one or more unitoperation, including, but not limited to, a heat exchanger, a fuel cell,a dehumidifier, a radiator, a holding tank, etc. As used herein, “influid communication” refers to in fluid communication in the directionof flow of fluid through the system. Thus, unless there is a loop theoutlet of a tube cannot be in fluid communication with the inlet of thesame tube.

First Discussion

FIGS. 2-5 show an embodiment in which the fuel cell (207) is composed ofits principal elements, an anode section (212), a cathode section (213)and a cooling plate (214). The fuel cell cathode (213) is fed withoutside air or another oxygen source. The cathode exhaust (21 b) isoxygen depleted air with high humidity. The fuel cell (207) alsocontains a cooling plate (214) in which coolant from a coolant container(215) is flowed. The fuel cell coolant enters the fuel cell coolingplate (214) at a relatively low temperature and exits at a hightemperature, almost equivalent to the operating temperature of the fuelcell (207). This temperature can range between 40° C. to 120° C. The hotfuel cell coolant is used to heat up low concentration liquid desiccant(227) originating from a low concentration liquid desiccant container(219). This heating process occurs in the desiccant regenerator (216).As the liquid desiccant is heated, its solubility in water is reduced,therefore water is released and the liquid desiccant concentrationincreases. The water released from the liquid desiccant is capturedusing high humidity cathode exhaust air in the water recovery system(217). The high humidity cathode exhaust is at a temperature similar tothe operating temperature of the fuel cell, therefore it aids inmaintaining the liquid desiccant warm at a temperature ranging between40° C. to 160° C. and at a low solubility point. Water is diffused fromthe liquid desiccant to the high humidity cathode exhaust. Since thehigh humidity cathode exhaust air is at or close to 100% relativehumidity, the water released by the liquid desiccant condenses alongwith the water in the air. Water condensation is captured andtransferred to a water container (218). The water recovery system mayalso include a radiator further cools the air in the water recoverysystem (217), resulting in further release of water. The liquiddesiccant exiting the water recovery system (217) is at highconcentration and is stored in the high concentration liquid desiccantcontainer (221). Note that water release from the desiccant and watervapor condensation are both endothermic processes, which result incooling down of the liquid desiccant in the water recovery system (217).

High concentration liquid desiccant flows from the high concentrationliquid desiccant container (221) through a pump (223) to an airconditioning dehumidifier (20) that forms part of the desiccant airconditioning system (32). Outside air, that is warm and humid, entersthe air conditioning dehumidifier. The air conditioner dehumidifierenables fluid contact between the water in the air and the highconcentration liquid desiccant. The high concentration liquid desiccantabsorbs the water in the air, substantially reducing air humidity.Although this process is exothermic, the exothermicity occurs at thesurface of the desiccant, where humidity absorption occurs. Since theliquid desiccant has a specific heat, the rise in temperature is low,which reduces the elevation of air temperature. The air exiting the airconditioning dehumidifier (220) has low humidity and a temperaturesimilar to the outside air temperature. This air is then cooled using asensible heat coil (222) to an appropriate temperature for introductioninto the air conditioned space, thus resulting in conditioned lowhumidity cold air (211). The liquid desiccant leaving the airconditioning dehumidifier is of low concentration (i.e., is diluted),since it has absorbed a substantial amount of water vapor. This lowconcentration liquid desiccant flows to a low concentration liquiddesiccant container (219). Note that in this embodiment cooling thatoccurs in the sensible heat coil is aided through the introduction ofwater transported by pump (225) from the water container (218). Thiswater is used to create evaporative cooling of a portion or all of thelow humidity air.

Note that although FIG. 2 represents each of these componentsseparately, this is done for illustration purposes only, as FIG. 2 isdescribing functions not independent and distinct components. Case inpoint, the air conditioning dehumidifier (220) can be coupled with thesensible heat coil (222). In doing this, the liquid desiccant and theair can be cooled as dehumidification occurs, increasing theeffectiveness of the process (low temperature liquid desiccant hashigher water solubility). Examples of combined functions include theheat and mass exchange (HMX) devices described herein, including theembodiments shown in FIG. 6 (element 1166), 12 (element 1166), andothers.

Embodiments of the air conditioning dehumidifier (220) and of a coupledair conditioning dehumidifier (220) and sensible heat coil (222) areshown in FIG. 3, A and B, respectively. In FIG. 3A, outside air (228)enters the air conditioning dehumidifier (220) in a chamber that is influid connection with water from a liquid desiccant through a watervapor permeable barrier (237). The water vapor permeable barrier onlyallows transfer of water and water vapor between the liquid desiccantand the air. The high concentration liquid desiccant (230) flow behindthis water vapor permeable barrier (237) absorbs water from the air andexits with a reduced concentration (231). The chamber in which theliquid desiccant flows is backed with a barrier with high thermalconductivity that allows conductive heat transfer between the liquiddesiccant flow and outside air (228) flowing in a chamber (236). In thismanner, outside air (228) cools the liquid desiccant preventingtemperature increase and increasing the effectiveness of airdehumidification. The general architecture described in FIG. 3A can beachieved through repeating plates in a stacked arrangement or through ashell and tube design.

FIG. 3B shows an embodiment in which the air conditioning dehumidifier(220) is coupled with the sensible heat coil (222) to increase theeffectiveness of the air dehumidification process. In this case, outsideair (228) flows into the dehumidification chamber (235). The water fromthe air and the liquid desiccant is in fluid connection through a watervapor permeable barrier (237) that only allows water to flow. Highconcentration liquid desiccant (203) flows on the other side of themirco-porous barrier (237) and absorbs water from the air therebyreducing the liquid desiccant concentration (231). The dehumidificationchamber is in thermal connection with an evaporative cooling chamber(236). In the evaporative cooling chamber a portion or all of the lowhumidity air leaving the dehumidification chamber (235) is flowedthrough the evaporative cooling chamber. Water (232) is also flowed inthe evaporative cooling chamber within a water vapor permeable barrierthat only allows transfer of water or water vapor to the air flowing inthe evaporative cooling chamber (236). As water is absorbed by the lowhumidity air, its temperature decreases and the air reaches close to100% relative humidity. As air is being cooled, it also absorbs heatfrom the air being dehumidified in the air dehumidifier (235). Theprocess of cooling air as it is being dehumidified increases theeffectiveness of the dehumidification process. The process of heatingair as it is being humidified increases the effectiveness of theprocess. Therefore, the architecture shown in FIG. 3B exhibits a highereffectiveness than if evaporative cooling and air dehumidification werebeing conducted separately.

The embodiment of FIG. 3B can be constructed in a stack arrangement orin a tube and shell arrangement. More detailed configurations of theseheat and mass exchange (HMX) components can be found throughout thisdisclosure.

Similarly, the desiccant regenerator (216) and the water recovery system(217) can be made part of a single component that enhances theeffectiveness of heat transfer and water transfer processes. Anembodiment of this type of integration is shown in FIG. 4, where lowconcentration liquid desiccant (227) flows into a regeneration chamber(248). The regeneration chamber (248) is thermally connected to achamber (249) in which the coolant leaving the fuel cell (243) isflowing. The fuel cell coolant (243) heats the liquid desiccant (227)reducing its water solubility, and thus increasing its concentration.The regeneration chamber is in thermal and fluid connection with a waterrecovery chamber (247). Additionally, these two chambers are separatedby a water vapor permeable barrier (243) that only allows passage ofwater between fluids in the water recovery chamber (247) and theregeneration chamber (248). High humidity cathode exhaust (239) flowsthrough the water recovery chamber, heating the liquid desiccant andcollecting water. As humidity in the water recovery chamber (247)reaches saturation, water condensation results. Air and water leavingthe water recovery chamber is passed through a radiator that cools theair below its dew point and releasing additional liquid water. Theliquid water is collected in a receptacle (241) and then flowed into thesystem's water container (218). This general structure maintains theliquid desiccant warm throughout the regeneration process and throughoutthe process of humidification and condensation of water using cathodeair. Both of these processes are endothermic. The design of thisintegrated desiccant regenerator (216) and water recovery system (217)can be executed using repeating cells in a stack or through the use ofshell and tube design.

An example of a shell and tube design for the air conditioningdehumidifier and the sensible heat coil is shown in FIG. 5, whereoutside air flows within a multitude of water vapor permeable conduitsthat run the length of an enclosed cylindrical annulus. The water vaporpermeable conduits are only permeable to water and water vapor and donot allow leakage of liquid desiccant into the air. In the samecylindrical annulus, high concentration liquid desiccant (230) isflowed. The liquid desiccant absorbs water from the air as it flows onthe outside of the water vapor permeable conduits and leaves thecylindrical annulus with a low concentration liquid desiccant (232). Airleaving (211) the air dehumidification cylindrical annulus (235) is dry.A portion of this air (211) is redirected to flow within a multitude ofwater vapor permeable conduits within a cylindrical enclosure (236) inthermal connection and embedded (or forming part of) the cylindricalannulus where air being dehumidified (235). Water (232) is flowedthrough the external portion of the multiple water vapor permeableconduits within which dry air flows. In this way, the air is cooled asit is humidified. The cool air and water in the internal cylindricalchamber absorb heat from the outer cylinder dropping the temperature ofthe air leaving it (211). Note that the structure of flow could bereversed in order to enhance heat transfer and reduce pressure dropsdepending on the application. For example, water in the innercylindrical chamber (236) could flow within the water vapor permeableconduits and air could flow externally.

Second Discussion

A combined air conditioning power generation system is disclosed. Thesystem includes a closed loop liquid desiccant system that utilizesexhaust from the fuel cell to regenerate liquid desiccant used todehumidify air being supplied to a space to be air conditioned. Waterfrom the fuel cell exhaust and the liquid desiccant regeneration is alsoused to provide evaporative cooling to the air conditioning system.Power generated by the fuel cell is used to power the air conditioner,the building being cooled and, where excess power is produced, the powercan be sold back to the power grid or stored for future use (e.g., inbatteries, capacitors, etc.).

While FIGS. 13-18, FIGS. 6-11, and FIG. 12 are described using differentreference numbers, it should be understood that FIGS. 13 and 6 (and 12)relate to substantially identical embodiments. Thus, where a discussionof FIGS. 13-18 relate to an equivalent structure of FIGS. 6-11, itshould be understood that the description is equally applicable to thecorresponding structure of FIGS. 6-11, and vice versa. For example, thedehumidifier 1004 of FIG. 13 corresponds with the dehumidifier 112 ofFIG. 6; the evaporative cooling chamber 1006 of FIG. 13 corresponds tothe evaporative cooling unit 1166 of FIG. 6; the heat exchanger 1011 ofFIG. 13 corresponds to the heat exchanger unit 1210 of FIG. 6; the fuelcell components 1013/1014 of FIG. 13 correspond to the fuel cell 1114 ofFIG. 6; the water recovery device 1012 of FIG. 13 corresponds to thedesiccant regeneration unit 1159 of FIG. 6; the radiator 1017 of FIG. 13corresponds to the WR radiator 1198 of FIG. 6; the radiator 1016 of FIG.13 corresponds to the fuel cell coolant radiator 1224 of FIG. 6, the lowconcentration liquid desiccant tank 1001 (64) of FIG. 13 corresponds tothe low concentration liquid desiccant storage 1252 b (64) of FIG. 6;the high concentration liquid desiccant tank 1002 (62) of FIG. 13corresponds to the high concentration liquid desiccant storage 1252 a(62) of FIG. 6; and the water storage tank 1003 (54) of FIG. 13corresponds with the water tank 1256 (54) of FIG. 6. Similarcorrelations can be made with respect to FIG. 12.

As shown in FIGS. 6-11, the combined air conditioning power generationsystem 1110 can include a dehumidifier 1112, a fuel cell 114, and awater recovery (WR) unit 1116. The dehumidifier 1112 can include adehumidifier desiccant duct 1118 that contacts a dehumidifier air duct1120. The fuel cell 1114 can include a first electrode chamber 1122, asecond electrode chamber 1124, and fuel cell stack cooling plates 1126.The fuel cell stack cooling plates 1126 can be in thermal communicationwith the first and/or second electrode chambers 1122, 1124. In someembodiments, the first electrode 1122 is a cathode and the secondelectrode 1124 is an anode, while the first electrode 1122 is an anodeand the second electrode 1124 is a cathode in other embodiments.

The water recovery (WR) unit 1116 can include a WR desiccant duct 1128that contacts a WR air duct 1130. In some embodiments, the outlet 1132of the first electrode chamber 1122 (e.g., a cathode chamber or an anodechamber) can be in fluid communication with an inlet 1134 of the WR airduct 1130. In some embodiments, such as a solid oxide fuel cell (SOFC),the first electrode chamber 1122 can be an anode chamber, while thefirst electrode chamber 1122 can be a cathode chamber in otherembodiments. In some embodiments, the outlet 1136 of the dehumidifierdesiccant duct 1118 is in fluid communication with the inlet 1138 of theWR desiccant duct 1128. In some embodiments, the outlet 1140 of the WRdesiccant duct 1128 is in fluid communication with an inlet 1142 of thedehumidifier desiccant duct 1118. Examples of fuel cells useful in thesystem 1110 include, but are not limited to, proton exchange membranefuel cells, direct methanol/ethanol fuel cells, phosphoric acid fuelcells, solid oxide fuel cells, and molten carbonate fuel cells.

In some embodiments, a first duct can be in contact with a second duct,where the first duct passes through the second duct or the second ductpasses through the first duct. In some embodiments, the first duct canpass through the second duct and the direction of fluid flow in firstduct can be approximately perpendicular to the direction of fluid flowin the second duct. Such arrangements may apply to any ducts in contactwith one another disclosed herein.

In some embodiments, the dehumidifier desiccant duct 1118 can passthrough the dehumidifier air duct 1120. As shown in FIG. 7, in someembodiments, the dehumidifier desiccant duct 1118 can include one or aplurality of dehumidifier desiccant conduits 1144. In some embodiments,the direction of flow of the at least one dehumidifier desiccant tube1144 is angled relative to the direction of flow of the dehumidifier airduct 1120. In some embodiments, the direction of flow of the at leastone dehumidifier desiccant tube 1144 is approximately perpendicular(e.g., 90°±10°, or 90°±5°, or 90°±2.5°) to the direction of flow of thedehumidifier air duct 1120. In some embodiments, the dehumidifierdesiccant duct 1118 includes a plurality of dehumidifier desiccantconduits 1144, which may be staggered across the dehumidified air duct1120, as shown in FIG. 7 (similar arrangements are shown in FIGS. 8-11).

In some embodiments, the dehumidifier desiccant duct 1118 comprises aplurality of dehumidifier desiccant conduits 1144, and the dehumidifier1112 further includes a dehumidifier desiccant header 1150 a in fluidcommunication with inlets 1142 a of the plurality of dehumidifierdesiccant conduits 1144. In some embodiments, the inlet 1152 of thedehumidifier desiccant header 1150 a is in fluid communication with theoutlet 1140 of the WR desiccant duct 1128.

In some embodiments, the dehumidifier further includes a dehumidifierdesiccant header 1150 b in fluid communication with outlets 1142 b ofthe plurality of dehumidifier desiccant conduits 1136 a. In someembodiments, the outlet 1154 of the dehumidifier desiccant header 1150 bis in fluid communication with the inlet 1138 of the WR desiccant duct1128.

In some embodiments, the dehumidifier desiccant duct 1118 and thedehumidifier air duct 1120 are on opposite sides of, or share a commonwall comprising, a dehumidifier membrane 1146. In some embodiments, thedehumidifier membrane 1146 is permeable to water vapor, but otherwisedoes not allow the transport of liquids from one side of thedehumidifier membrane 1146 to the other. Such water vapor permeablemembranes and their properties are described throughout this disclosure.

In some embodiments, the dehumidifier membrane 1146 allows water vaporin the air within the dehumidifier air duct 1120 to cross thedehumidifier membrane 1146 and pass into a desiccant stream within thedehumidifier desiccant duct 1118. In some embodiments, as a result ofwater vapor passing from the air in the dehumidifier air duct 1120 intothe dehumidifier desiccant duct 1118, the liquid desiccant streamexiting the dehumidifier desiccant duct 1118 has a lower concentrationof desiccant (higher concentration of water) than the liquid desiccantstream entering the dehumidifier desiccant duct 1118, and the air streamexiting the dehumidified air duct 1120 has a lower humidity than the airstream entering the dehumidified air duct 1120. The system 1110 can beoperated so that the contents of the dehumidifier desiccant duct 1118 donot pass through to the air in the dehumidifier air duct 1120.

In some embodiments, the water recovery unit 1116 includes a desiccantregeneration unit 1159 that includes the WR desiccant duct 1128 and theWR air duct 1130. In some embodiments, the WR desiccant duct 1128 andthe WR air duct 1130 are on opposite sides of, or share a common wallcomprising, a WR membrane 1148. In some embodiments, the WR membrane1148 is permeable to water vapor, but otherwise does not allow thetransport of liquids from one side of the WR membrane 1148 to the other.For instance, the WR membrane 1148 can allow water in a desiccant streamwithin the WR desiccant duct 1128 to cross the WR membrane 1148 and passinto the cathode exhaust stream within the WR air duct 1130.

In some embodiments, the WR membrane 1148 allows water from the WRdesiccant duct 1128 to cross the WR membrane 1148 and pass into theexhaust stream within the WR air duct 1130. In some embodiments, as aresult of water vapor passing from the liquid desiccant in the WRdesiccant duct 1128 into the WR air duct 1130, the liquid desiccantstream exiting the WR desiccant duct 1118 has a higher concentration ofdesiccant (lower concentration of water) than the liquid desiccantstream entering the WR desiccant duct 1128, and the exhaust streamexiting the WR air duct 1130 has a higher humidity or water content thanthe exhaust stream entering the WR air duct 1130. The system 1110 can beoperated so that only water vapor passes from the WR desiccant duct 1128to the WR air duct 1130.

In some embodiments, the WR desiccant duct 1128 can pass through the WRair duct 1130. As shown in FIG. 8, in some embodiments, the WR desiccantduct 1128 can include a plurality of WR desiccant conduits 1156. In someembodiments, the direction of flow of the at least one WR desiccant tube1156 is angled relative to the direction of flow of the WR air duct1130. In some embodiments, the direction of flow of the at least one WRdesiccant tube 1156 is approximately perpendicular (e.g., 90°±10°, or90°±5°, or 90°±2.5°) to the direction of flow of the WR air duct 1120.In some embodiments, the WR desiccant duct 1128 includes a plurality ofdehumidifier desiccant conduits 1156, which may be staggered across thedehumidified air duct 1130, as shown in FIG. 8 (similar arrangements areshown in FIGS. 7 and 9-11).

In some embodiments, the WR desiccant duct 1128 comprises a plurality ofWR desiccant conduits 1156, and the system 1110 includes a WR desiccantheader 1160 a in fluid communication with inlets 1138 a of the pluralityof WR desiccant conduits 1156. In some embodiments, the inlet 1162 ofthe WR desiccant header 1160 a is in fluid communication with the outlet1136 of the dehumidifier desiccant duct 1118.

As shown in FIG. 8, in some embodiments, the system also includes a WRdesiccant header 1160 b in fluid communication with outlets 1140 b ofthe plurality of dehumidifier desiccant conduits 1156. In someembodiments, the outlet 1164 of the WR desiccant header 1160 b is influid communication with the inlet 1142 of the dehumidifier desiccantduct 1118.

As shown in FIG. 9, in some embodiments, the combined air conditioning,power generation system 1110 includes an evaporative cooling (EC) unit1166 that includes an EC air duct 1168 for contacting cooling air withan EC water duct 1170 and an EC desiccant duct 1172. In someembodiments, the EC water duct(s) 1170 and the EC desiccant duct(s) 1172are arranged so that fluid in the EC air duct 1168 encounters the ECwater duct(s) 1170 and the EC desiccant duct(s) 1172 sequentially. Insome embodiments, the EC water duct(s) 1170 and the EC desiccant duct(s)1172 are interspersed.

The EC water duct 1170 can transfer water droplets or vapor into coolingair passing through the EC air duct 1168 in order to providepsychrometric or evaporative cooling of the cooling air. For example, insome embodiments, the EC water duct 1170 can include an EC membrane 1174that is permeable to water vapor for providing evaporative cooling ofthe cooling air passing through the EC air duct 1168. In otherembodiments, the EC water duct 1170 can spray droplets of water into thecooling air passing through the EC air duct 1168. An example of such asprayer is shown in FIG. 33. In some embodiments, the EC water duct 1170can include a plurality of EC water conduits 1170 a. In some embodimentsthe EC water duct 1170 can be adapted to allow water to flow on theexterior portion of the EC water duct 1170 (e.g., orifices positionedalong an upper portion of the EC water duct 1170).

In some embodiments, the only outlet of the EC water duct 1170 isthrough nozzles or the walls of the EC water duct (e.g., throughorifices or the EC membrane 1174). In some embodiments, the system 1110also includes an EC water pump 1176 in fluid communication with the ECwater duct 1170 for maintaining a target pressure within the EC waterduct 1170. This allows the system to control the amount of psychrometriccooling utilized in the evaporative cooling unit 1166. The pressuremaintained in the EC water duct 1170 should be sufficient to cause adesired amount of water molecules to pass into the EC air duct 1168. Insome embodiments, the EC water pump 1176 is controlled using levelsensor(s) or switch(s) 1177 which maintains a certain water levelcorresponding to a certain water flow.

In some embodiments, such as the one shown in FIG. 9, the EC desiccantduct 1172 can be one or more EC desiccant conduits 1172 a. In someembodiments, the walls of the EC desiccant conduits 1172 a can have ahigh thermal conductivity and be impermeable to the desiccant stream andthe water in the air stream. This allows the chilled air that hasundergone evaporative cooling as a result of the water released by theEC water duct 1170 to cool the desiccant stream in the EC desiccant duct1172 before it enters the dehumidifier 1112.

In some embodiments, an inlet 1178, 1178 a of the EC water duct 1170 canbe in fluid communication with an outlet 1158 of the WR air duct 1130.

In some embodiments, the evaporative cooling unit 1166 can also includean EC water header 1180 in fluid communication with inlets 1178 a of theplurality of EC water conduits 1170 a. In some embodiments, an inlet1182 of the EC water header 1180 is in fluid communication with theoutlet 1158 of the WR air duct 1134. In some embodiments, the outlets1184 of the plurality of EC water conduits 1170 a can be in fluidcommunication with an end cap 1186 with no outlet.

In some embodiments, the evaporative cooling unit 1166 also includes anEC desiccant header 1188 a in fluid communication with inlets 1190 ofthe plurality of EC desiccant conduits 1172 a. In some embodiments, theinlet 1192 of the EC desiccant header 1188 a is in fluid communicationwith the outlet 1140 of the WR desiccant duct 1128.

In some embodiments, the evaporative cooling unit 1166 also includes anEC desiccant header 1188 b in fluid communication with outlets 1194 ofthe plurality of EC desiccant conduits 1172 a. In some embodiments, theoutlet 1196 of the EC desiccant header 1188 b is in fluid communicationwith an inlet 1142, 1152 of the dehumidifier desiccant duct 1120 (e.g.,dehumidified desiccant conduits 1144 or dehumidifier desiccant header1150 a), an inlet 1190, 1190 a of the EC desiccant duct 1172, 1172 a, orboth.

As shown in FIG. 10, in some embodiments, the dehumidifier 1112 and theevaporative cooling unit 1166 can be part of a common housing and theoutlet 1194 of the EC desiccant duct 1172 can be directly connected tothe inlet 1142 of the dehumidifier desiccant duct 1118 by a connectingtube or pipe 1258. FIG. 10 is one embodiment of a cross-sectional viewof the air ducts 1120/1169 of FIG. 6 taken along cut line 10-10, wherethe direction of air flow is into the page.

In some embodiments, as shown in FIG. 6, the system 1110 includes awater recovery (WR) radiator 1198. The WR radiator 1198 can include a WRradiator cooling duct 1200 and a WR radiator water feed duct 1202. TheWR radiator water feed duct 1202 can be a radiator and the WR radiatorcooling duct 1200 can be adapted for blowing ambient air into contactwith the WR radiator water feed duct 1202. A WR radiator fan 1203 can bepositioned to force air through the WR radiator cooling duct 1200 andonto the WR radiator water feed duct 1202.

An outlet 1158 of the WR air duct 1130 can be in fluid communicationwith an inlet 1204 of the WR radiator water feed duct 1202. In someembodiments, the WR radiator water feed duct 1202 has two outlets: a WRradiator water line 1206 and a WR radiator exhaust 1208. The WR radiatorwater line 1206 can be in fluid communication with an inlet 1178 of theEC water duct 1170. In some embodiments, the WR radiator exhaust 1208can be in fluid communication with the environment, while the WRradiator exhaust 1208 can be in fluid communication with a space to beconditioned (e.g., heated) in other embodiments.

In some embodiments, the system 1110 includes a heat exchanger (HX) unit1210 that includes a HX desiccant duct 1212 contacting a HX coolant duct1214. In some embodiments, the HX desiccant duct 1212 is in thermalcommunication with the HX coolant duct 1214. In some embodiments, the HXdesiccant duct 1212 is not in fluid communication with the HX coolantduct 1214. The heat exchanger unit 1210 can be a counter-flow heatexchanger, such as a counter-flow, plate heat exchanger.

In some embodiments, an inlet 1216 of the HX desiccant duct 1212 is influid communication with the outlet 1136 of the dehumidifier desiccantduct 1118. In some embodiments, an outlet 1218 of the HX desiccant duct1212 is in fluid communication with an inlet 1138 of the WR desiccantduct 1128. In some embodiments, an inlet 1220 of the HX coolant duct1214 is in fluid communication with a fuel cell stack cooling plateoutlet 1125. In some embodiments, an outlet 1222 of the HX coolant duct1214 is in fluid communication with a fuel cell stack cooling plateinlet 1127.

In some embodiments, the system 1110 includes a fuel cell coolant (FCC)radiator 1224. In some embodiments, the FCC radiator 1224 includes a FCCcoolant duct 1226 and a FCC radiator air duct 1228. The FCC coolant duct1226 can be a radiator and the FCC radiator air duct 1228 can be adaptedfor blowing ambient air into contact with the FCC coolant duct 1226. AFCC radiator fan 1229 can be positioned to force air through the FCCradiator air duct 1228 and impinge the air on the FCC coolant duct 1226.

In some embodiments, an inlet 1230 of the FCC coolant duct 1226 is influid communication with a HX coolant duct outlet 1222 and an outlet1232 of the FCC coolant duct 1226 is in fluid communication with a fuelcell stack cooling plate inlet 1127. In some embodiments, the FCCradiator air duct 1228 is open to ambient air (e.g., the outdoors) atboth the inlet 1234 and the outlet 1236.

In some embodiments, the outlet 1236 of the FCC radiator air duct 1228can be in fluid communication with a space in need of conditioned air,e.g., a building. In such instances, the air exiting the outlet 1236 ofthe FCC radiator air duct 1228 can be used to heat the space.

As shown in FIG. 12, in some embodiments either or both of the radiators1198, 1224 can be replaced by liquid (e.g., water) cooled heatexchangers 1260, 1270. In such embodiments, the outlet of therefrigerant line can be in fluid communication with a water supply, suchas a building water supply, for providing hot water.

In some embodiments, the water recovery line 1244 can include a waterrecovery line heat exchanger 1260. The water recovery line heatexchanger 1260 can include a WRL refrigerant duct 1262 and a WR waterfeed duct 1202. The WR water feed duct 1202 can be in thermalcommunication, but not fluid communication, with the WRL refrigerantduct 1262. In some embodiments, a domestic or industrial water supplycan be in fluid communication with an inlet 1264 of the WRL refrigerantduct 1262 and the outlet 1266 of the WRL refrigerant duct 1262 canprovide hot water for domestic or industrial use. Thus, in someembodiments, the water recovery line heat exchanger 1260 can function asa hot water heater, with the outlet 1266 providing hot water fordomestic or industrial use.

An outlet 1158 of the WR air duct 1130 can be in fluid communicationwith an inlet 1204 of the WR water feed duct 1202. In some embodiments,the WR water feed duct 1202 has two outlets: a WR water line 1206 and aWR exhaust 1208. The WR water line 1206 can be in fluid communicationwith an inlet 1178 of the EC water duct 1170. In some embodiments, theWR exhaust 1208 can be in fluid communication with the environment,while the WR radiator exhaust 1208 can be in fluid communication with aspace to be conditioned (e.g., heated) in other embodiments.

In some embodiments, the FC coolant loop 1242 can include a coolantrecovery line heat exchanger 1270. The CRL heat exchanger 1270 caninclude a FCC coolant duct 1226 and a CRL refrigerant duct 1272. The FCCcoolant duct 1226 can be in thermal communication, but not fluidcommunication, with the CRL refrigerant duct 1272. In some embodiments,a domestic or industrial water supply can be in fluid communication withan inlet 1274 of the CRL refrigerant duct 1272 and the outlet 1276 ofthe CRL refrigerant duct 1272 can provide hot water for domestic orindustrial use. Thus, in some embodiments, the CRL heat exchanger 1270can function as a hot water heater, with the outlet 1266 providing hotwater for domestic or industrial use.

In some embodiments, an inlet 1230 of the FCC coolant duct 1226 is influid communication with a HX coolant duct outlet 1222 and an outlet1232 of the FCC coolant duct 1226 is in fluid communication with a fuelcell stack cooling plate inlet 1127.

As shown in FIG. 11, in some embodiments where a plurality of conduits(t)(e.g., 1144, 1156, 1172 a, 1170 a, etc.) is used, the plurality ofconduits can be held in a desired configuration by end plates 1238 a,1238 b. The end plates 1238 a, 1238 b can be coupled to the conduits (t)so that the ends of the conduits (t) are not blocked and there is afluid-tight seal between the outside of the conduits and each end plate1238 a, 1238 b. The end plates 1238 a, 1238 b help prevent mixing of thestreams in the different ducts, particularly where cross-flowarrangements and headers are used.

In some embodiments, the system 1110 can be adapted to include adesiccant loop 1240, a fuel cell coolant loop 1242, and a water recoveryline 1244. Each of these loops 1240, 1242, 1244 can include one or morecontrol pumps 1246, 1248, 1250, respectively, for transporting therelevant fluid through the loop. Each of these loops can have no fluidcommunication with the other loops, except for the transfer of watervapor that occurs in the desiccant regeneration unit 1159.

The desiccant loop 1240 can include the dehumidifier desiccant duct 1118in fluid communication with the HX desiccant duct 1212 in fluidcommunication with the WR desiccant duct 1128 in fluid communicationwith the EC desiccant duct 1172 in fluid communication with thedehumidifier desiccant duct 1118. The desiccant loop 1240 can alsoinclude a high concentration liquid desiccant tank 1252 a, a lowconcentration liquid desiccant tank 1252 b, or both 1252 a, 1252 b.Although the low concentration liquid desiccant tank 1252 b is shownbetween then dehumidifier desiccant duct 1118 in fluid communicationwith the HX desiccant duct 1212, it will be understood that the lowconcentration liquid desiccant tank 1252 b can also be positionedbetween the HX desiccant duct 1212 and the WR desiccant duct 1128.

The fuel cell coolant loop 1242 can include the fuel cell stack coolingplates 1126 in fluid communication with the HX coolant duct 1214 influid communication with the FCC coolant duct 1226 in fluidcommunication with the fuel cell stack cooling plates 1126.

The water recovery line 1244 can start with the supersaturated exhaustexiting the WR air duct 1130 in fluid communication with the WR radiatorwater feed duct 1202 in fluid communication with the WR radiator waterline 1206 in fluid communication with the EC water duct 1170.

Also described is a method of operating a combined air conditioningpower generation system 110 as described herein. The method can be acontinuous method. The method can include dehumidifying an air streamusing a liquid desiccant stream; and regenerating the liquid desiccantstream using an exhaust stream from an electrode chamber of a fuel cell.In some embodiments, the air stream and the liquid desiccant stream arein fluid communication through a dehumidifier membrane 146 that allowsmoisture in the air to pass into the liquid desiccant stream.

The exhaust stream can be from an anode chamber or a cathode chamber ofa fuel cell. The exhaust stream can have a high humidity (e.g., >70%RH, >80% RH, >90% RH) and a temperature above room temperature(e.g., >40° C., >50° C., >60° C., >70° C., >80° C., >90° C., or >100°C.).

In some embodiments, the method can also include capturing cooling waterfrom the exhaust stream used in the regenerating step; and cooling theliquid desiccant stream before the dehumidifying step. The cooling stepcan include evaporative cooling of the liquid desiccant stream using thecooling water.

In some embodiments, the capturing step includes contacting the exhauststream with a refrigerant stream. In some embodiments, the refrigerantstream is used for air conditioning or as a domestic or commercial watersupply. The method can also include any of the interactions describedwith respect to the particular unit operations described herein.

A dehumidifier system that uses a liquid desiccant, such as thosedisclosed herein, to dehumidify an incoming air stream for airconditioning purposes is described. The design of the dehumidifier issuch that heat energy is continually being removed throughout thedehumidification process by means of, but not necessarily exclusivelyof, air flow from the atmosphere, water recovered from the liquiddesiccant during its regeneration process, and/or through the flow ofcooled liquid desiccant. The system is designed in such a way that thewater that is absorbed from the ambient air and that enters into theliquid desiccant stream is recovered. This water recovery system uses aliquid cooled fuel cell stack and utilizes the heat produced from itsoperation to increase the temperature of the liquid desiccant andpromote water desorption. The fuel cell's cathode exhaust air andhumidity is also used to promote water recovery by using this stream asa water collection, conveyance and precipitation agent.

The use of liquid desiccant in the systems described herein enablesregulation of the rate of air dehumidification by controlling the liquiddesiccant flow. Additionally, the liquid desiccant dehumidifies airthrough a water vapor permeable barrier that can be composed of amicroporous polymer or a water permeable polymer. In this way, liquiddesiccant entrainment into the air conditioning supply air stream isprevented. The dehumidification process is isothermal, which increasesthe effectiveness of the air dehumidification process. This in turnresults in lower liquid desiccant flow rates and reduces the size, costand complexity of the liquid desiccant conveyance systems, such aspumps, valves, and line sizes. The continuous operation of the systemrelies on the capacity to regenerate the liquid desiccant from a lowconcentration (high water content) state to a high concentration (lowwater content) state. The way the fuel cell is used and the designs ofthe system components enables liquid desiccant regeneration to resultsin recovery of the water obtained from the liquid desiccant and in thegeneration of electricity. The resulting device, an isothermal airdehumidifier, that generates electricity as a by-product of itsoperation, has enormous value since it increases the overall efficiencyof air-conditioning.

FIG. 13 shows the air dehumidification system with all its principalcomponents. A dehumidifier (1004) takes ambient air (1009) which has acertain temperature and humidity level. The ambient air enters adehumidification chamber (1005) where high concentration liquiddesiccant that has been chilled in an evaporative cooling chamber (1006)absorbs the air's humidity. The liquid desiccant exits thedehumidification chamber (1005) at a lower concentration than when itenters. This low concentration liquid desiccant (1001) is stored.Exiting the dehumidification chamber is low humidity building supply air(1010). The evaporative cooling chamber is also fed with ambient air(1007) that is being humidified and in this manner its temperaturereduced to its wet bulb temperature. The high concentration liquiddesiccant flowing in the evaporative cooling chamber (1006) is cooled bythe humidified ambient air. The humid air (1008) leaving the evaporativecooling chamber is exhausted to the environment. The high concentrationliquid desiccant (1002) is stored in a vessel, as is the water (1003).

In order to maintain the process of dehumidification, water (1003) andhigh concentration liquid desiccant (1002) must be replenished. This isdone through a water recovery and desiccant regeneration system thatuses the heat, water and fuel cell cathode exhaust air. Liquid fuel cellcoolant (1015), which can be any suitable fuel cell cooling fluid thatcould include but is not restricted to be water, ethylene glycol, oils,polymer blends, or a combination thereof, flows into the fuel cell stackcooling plates (1013) collecting the heat generated by the operation ofthe fuel cell stack. Fuel cell stack operation produces electricity(1020) as a by-product. The fuel cell coolant exiting the fuel cellstack cooling plates (1013) is then passed through a heat exchanger(1011). This heat exchanger enables heat transfer between a stream oflow concentration liquid desiccant and the fuel cell coolant streamexiting the fuel cell stack cooling plates (1013). In doing so, thetemperature of the low concentration liquid desiccant stream isincreased, reducing the amount of water in solution with the desiccant.The process of dissolution of water from the liquid desiccant isendothermic. The fuel cell coolant leaving the heat exchanger (1011) isfurther cooled using a radiator (1016). The heat exchanger (1011) issuch that all its parts wetted by the low concentration liquid desiccantare made of materials that are chemically compatible with the liquiddesiccant such as plastics, polymer blends, and coated metals. Anembodiment of the heat exchanger (1011) design will be discussed laterin this document.

The liquid desiccant leaving the heat exchanger (1011) is then suppliedto a water recovery device (1012). The water recovery device is alsosupplied with air leaving the fuel cell stack anode chamber (1014). Thefuel cell cathode chamber (1014) is supplied with ambient air (1019).This oxygen in this ambient air (1019) is reacted in the fuel cell stackcathode chamber (1014) to form water. The air leaving the fuel cellstack cathode chamber (1014) is warm, at a temperature close to, orequal to, the operating temperature of the fuel cell stack. Althoughwarm, this air is typically super-saturated and typically has liquidwater. This air is supplied to the water recovery device so that water,no longer in solution with the liquid desiccant flowing in the waterrecovery device (1012) flows from the liquid desiccant to the air side.The partial pressure of water in the air side is lower than in theliquid desiccant side. These sides of the water recovery device (1012)are separated by a water vapor permeable barrier that can be composed ofmicro-porous plastic or a hygroscopic polymer or a combinationtherefore. This barrier, does not permit liquid desiccant or air to mixwithin the water recovery device (1012). Air leaving the water recoverydevice is further cooled using ambient air in a radiator (1017). Theliquid water condensed is collected and pumped to a water reservoir(1003). The air leaving the radiator (1017) is exhausted. Highconcentration liquid desiccant exits the water recovery device (1012)and is pumped or conveyed to a high concentration liquid desiccantreservoir (1002).

In some embodiments, the systems uses a barrier (1021) between theliquid desiccant and the streams with which this fluid needs to transferheat and water. This barrier is composed of a plastic or polymer that ischemically compatible with the liquid desiccant.

The barrier (1021) can be arranged into a bundle of conduits (1022).This bundle of conduits (1022) can be arranged in a cylindrical orrectangular manner (as is shown in FIG. 14). The ends of this bundle ofconduits (1022) can be stabilized (or embedded) in a framed (1023) asshown in FIG. 14. The frame can then be filled with a pourable andhardening polymer (1024) so that the openings to the ends of the bundleconduits (1022) are exposed and the body of bundle of conduits (1022) isseparated from these ends. The same can be done with the other end ofthe bundle of conduits (1022).

The result is a plastic structure (1024) as shown in FIG. 11. Because ofthis structure (1024) liquid desiccant can pass within the individualcylindrical barriers (1021) and air or other fluids can pass across thebody of the cylindrical barrier (1021). As previously discussed thebarriers (1021) can be constructed of many materials. However, if watertransfer is desired between the fluid passing across the bundle ofconduits (1022) and the liquid desiccant passing within the individualbarriers (1021) in the bundle of conduits (1022), then the material usedfor the barriers (1021) can be made of any of the compatible materialsin a micro-porous configuration. The size of the pores must be largeenough to enable the passage of water molecules and not the passage ofair molecules such as nitrogen and oxygen. Note that the water moleculeis smaller than these other molecules. An alternative to the use ofmicro-porous plastics is the use of water permeable plastics that allowwater transport across them. One such plastic is Nafion, though othersare described herein.

FIG. 15 shows the dehumidification chamber (1005) of the airdehumidifier (1004), where ambient air flow (1009) flows through theexternal portion of the bundle of conduits (1022) in the structure(1024). High concentration liquid desiccant would flow within thebarriers (1021) and would absorb humidity from the air.

FIG. 16 shows a top view of the dehumidification chamber (1005) of theair dehumidifier (1004). This shows that the internal portion of thebarriers (1021) in the tube bundle (1022) are in fluid connection witheach and that liquid desiccant is introduced into them via a singleentry port. A cap (1025 a) provides a chamber in which liquid desiccantis distributed into the inner portion of the individual barrier (1021).A similar cap (1025 b) exists on the other side of the structure (1024).This cap (1025 b) collects the outflow of liquid desiccant from theindividual barriers (1021).

FIG. 17 shows a more detailed conception of the air dehumidifier (1004).As shown, the dehumidifier is composed of two chambers, the airdehumidification chamber (1009) and the evaporative cooling chamber(1006). Both chambers make use of the tubular bundle structure (1024) totransfer heat or heat and water. In the evaporative cooling chamber(1006), ambient air (1007) flows through one or two structures (1024 a,1024 b). The first structure (1024 a) has water flowing within its tubebundle (1022 a). The material barriers (1021) are made of microporousplastic, which enables water seepage from the tube bundle to the air. Asair absorbs the water, its temperature drops and approaches the wet bulbtemperature. Note that there is no outflow port in the cap (1025) ofthis structure (1024). This is because water is continually beingdrained through entrainment in air. Regulation of water flow into thisstructure could use a constant pressure device (1027) that ensures waterpressure in the tube bundle is maintained within a certain range. Aswater is absorbed by the air, water pressure will decrease causing thevalve to open allowing water to enter the structure (1024 a). Anothermethod uses water transport through capillary action within the barriers(1021). As water is consumed, and the barrier is dried, water enters thetube. Depending on the way in which water is introduced into theconduits or on the external surface of the tube, the orientation of thetube bundle may be vertical or horizontal.

The lower temperature air flows through a second structure (1024 b) inthe evaporative cooling chamber (1006). High concentration liquiddesiccant flows within this structure (1024 b). Since there is no desireto transport water between the air and the liquid desiccant, but onlyheat, the barriers (1021) in this structure (1024) are constructed of amaterial that is not porous or permeable to water. The material and thestructure of the tube bundle (1022) are designed solely for the purposeof transferring heat. The liquid desiccant (1026) leaving theevaporative cooling chamber (1006) of the air dehumidifier (1004) iscool, and close to the wet bulb temperature of the ambient air. Thecooled liquid desiccant (1026) then enters the dehumidifying chamber(1005) of the dehumidifier.

As shown in FIG. 18, the mechanical arrangement of the air dehumidifier(1004) can be in a single air duct that is divided so that a portion ofthe air passes through the evaporative cooling chamber (1006) and theother portion passes through the air dehumidification chamber (1005). Inthis figure, the air is flowing into the page. The advantage of thisconfiguration is that the parts can be co-located and a single airsource can be used.

In all the arrangements, the diameter and material used for the barriercan vary depending on the particular function of the structure. Lowerdiameter barriers result in higher surface are to volume ratio, whichenhances mass transport and heat transfer. However, lower diameterincreases the pressure drop through the barrier, so the number ofbarriers in a tube bundle has to increase. The material of the barriercan vary based on function. For example, the barriers in the structureused in the water recovery device (1012) can have an outer surfacematerial that is hydrophobic or super-hydrophobic, such as Teflon forexample. In this way, water droplets formed would roll easily from thetube into a collection basin. The embodiments for the water recoverydevice (1012) include those with a vertical tube bundle. In a similarmanner, the barriers used in the evaporative cooling chamber (1006)structure could have an outer material that is hydrophilic. In this waywater accumulated in the outer portion of the barrier would not roll offthe tube but instead remain until fully dried by incoming ambient air.

A first specific system combined air conditioning power generationsystem can include a dehumidifier comprising a dehumidifier desiccantduct that contacts a dehumidifier air duct, a fuel cell comprising anelectrode chamber; and a water recovery (WR) unit comprising a WRdesiccant duct that contacts a WR air duct, wherein an outlet of theelectrode chamber is in fluid communication with an inlet of said WR airduct, wherein an outlet of said dehumidifier desiccant duct is in fluidcommunication with an inlet of the WR desiccant duct, and wherein anoutlet of the WR desiccant duct is in fluid communication with an inletof said dehumidifier desiccant duct.

A second specific system can be the first specific system, wherein saiddehumidifier desiccant duct and said dehumidifier air duct are onopposite sides of a dehumidifier membrane, wherein the dehumidifiermembrane is permeable to water vapor.

A third specific system can be the second specific system, wherein saiddehumidifier membrane allows water in the air within the dehumidifierair duct to cross the dehumidifier membrane and pass into a desiccantstream within the dehumidifier desiccant duct.

A fourth specific system can be any of the foregoing specific systems,wherein the dehumidifier desiccant duct comprises at least onedehumidifier desiccant tube.

A fifth specific system can be any of the foregoing specific systems,wherein said WR desiccant duct and said WR air duct are on oppositesides of a WR membrane, wherein the WR membrane is permeable to watervapor.

A sixth specific system can be the fifth specific system, wherein saidWR membrane allows water in a desiccant stream within the WR desiccantduct to cross the WR membrane and pass into the cathode exhaust streamwithin the WR air duct.

A seventh specific system can be any of the foregoing specific systems,wherein the WR desiccant duct comprises a plurality of WR desiccantconduits.

An eighth specific system can be any of the foregoing specific systems,wherein said dehumidifier desiccant duct comprises a plurality ofdehumidifier desiccant conduits, and said dehumidifier further comprisesa dehumidifier desiccant header in fluid communication with inlets ofsaid plurality of dehumidifier desiccant conduits, wherein an inlet ofthe dehumidifier desiccant header is in fluid communication with theoutlet of the WR desiccant duct.

A ninth specific system can be any of the foregoing specific systems,further comprising an evaporative cooling (EC) unit comprising an EC airduct for sequentially contacting cooling air with an EC water duct andan EC desiccant duct, wherein said EC water duct comprises an ECmembrane that is permeable to water vapor for providing evaporativecooling of the cooling air passing through the EC air duct.

A tenth specific system can be the ninth specific system, furthercomprising a WR radiator, comprising a WR radiator cooling duct and a WRradiator water feed duct, wherein an outlet of the WR air duct is influid communication with an inlet of the WR radiator water feed duct,wherein the WR radiator water feed duct has two outlets, a WR radiatorwater line and a WR radiator exhaust, wherein said WR radiator waterline is in fluid communication with an inlet of said EC water duct.

An eleventh specific system can be the ninth specific system, furthercomprising an EC water pump in fluid communication with the EC waterduct for maintaining a target pressure in the EC water duct.

A twelfth specific system can be the ninth system, wherein the onlyoutlet of the EC water duct is through the EC membrane.

A thirteenth specific system can be the ninth specific system, whereinthe EC water duct comprises a plurality of EC water conduits.

A fourteenth specific system can be the ninth specific system, whereinan outlet of the WR desiccant duct is in fluid communication with aninlet of the EC desiccant duct, wherein the EC desiccant duct compriseswater impermeable walls, and wherein an EC desiccant duct outlet is influid communication with the inlet of the WR desiccant duct.

A fifteenth specific system can be the ninth specific system, whereinthe EC desiccant duct comprises a plurality of EC desiccant conduits.

A sixteenth specific system can be the ninth specific system, furthercomprising a heat exchanger (HX) unit comprising a HX desiccant ductcontacting a HX coolant duct, wherein: an inlet of the HX desiccant ductis in fluid communication with the outlet of the dehumidifier desiccantduct; an outlet of the HX desiccant duct is in fluid communication withan inlet of the WR desiccant duct; an inlet of the HX coolant duct is influid communication with a fuel cell stack cooling plate outlet; and anoutlet of the HX coolant duct is in fluid communication with a fuel cellstack cooling plate inlet.

A seventeenth specific system can be the sixteenth specific system,further comprising a fuel cell coolant (FCC) radiator, comprising a FCCcoolant duct and a FCC radiator air duct, wherein an inlet of the FCCcoolant duct is in fluid communication with a HX coolant duct outlet andan outlet of the FCC coolant duct is in fluid communication with a fuelcell stack cooling plate inlet.

An eighteenth specific system can be the sixteenth specific system,wherein an inlet and an outlet of the FCC radiator air duct are in fluidcommunication with ambient air.

A nineteenth specific system can be the sixteenth specific system,wherein the fuel cell further comprises a second electrode chamber andfuel cell stack cooling plates in thermal communication with the firstand second electrode chambers.

A twentieth specific system can be any of the foregoing specificsystems, wherein the fuel cell further comprises a second electrodechamber and fuel cell stack cooling plates in thermal communication withthe first and second electrode chambers.

A twenty-first specific system can be any of the foregoing specificsystems, wherein the electrode chamber is a cathode chamber.

A twenty-second specific system can be any of the foregoing specificsystems, wherein the electrode chamber is an anode chamber.

A first continuous method of operating a combined air conditioning powergeneration system, comprises: dehumidifying an air stream using a liquiddesiccant stream; and regenerating the liquid desiccant stream using anexhaust stream from an electrode chamber of a fuel cell.

A second specific method can be the first specific method furthercomprising, capturing cooling water from the exhaust stream used in theregenerating step; and cooling the liquid desiccant stream before thedehumidifying step, wherein the cooling step comprising evaporativecooling of the liquid desiccant stream using the cooling water.

A third specific method can be the second specific method, wherein thecapturing step comprises contacting the exhaust stream with arefrigerant stream, and the refrigerant stream is used for airconditioning or as a domestic or commercial water supply.

A fourth specific method can be the second specific method, wherein theair stream and the liquid desiccant stream are in fluid communicationthrough a dehumidifier membrane that allows moisture in the air to passinto the liquid desiccant stream.

A fifth specific method can be any of the foregoing specific methods,wherein the air stream and the liquid desiccant stream are in fluidcommunication through a dehumidifier membrane that allows moisture inthe air to pass into the liquid desiccant stream.

Third Discussion

FIG. 19a shows an embodiment of a heat and mass transfer device (2100)with distinct and separate heat transfer conduits (2001) and masstransfer conduits (2002), while FIG. 19b is a cross-sectional view ofFIG. 19a . The mass transfer conduits (2002) are retained by and sealedagainst two mass transfer manifold plates (2012). Longer heat transferconduits (2001) are retained by and sealed against two heat transfermanifold plates (2011) and two mass transfer manifold plates (2012). Asshown in the figures, in some embodiments, the coolant (2003) isintroduced into heat transfer conduits (2001) parallel to andinterspersed among mass transfer conduits (2002) carrying liquiddesiccant (2004), which is introduced between the heat transfer manifoldplate (2011) and the mass transfer manifold plate (2012). The air to bedehumidified (2005) passes perpendicular to the axes of the masstransfer conduits (2002) and the heat transfer conduits (2001).Dehumidified air (2006) exits the device after it passes by theplurality of heat transfer conduits (2001) and mass transfer conduits(2002). As water vapor in the air to be dehumidified (2005) is absorbedby the liquid desiccant (2004) in the mass transfer conduits (2002),heat is transferred to the air being dehumidified (2005). This heat isthen transferred from the air being dehumidified (2005) to the coolant(2003) in the heat transfer conduits (2001). In this fashion, the airbeing dehumidified (2005) acts as a heat transfer medium between theliquid desiccant (2004) and the coolant (2003), and the air beingdehumidified (2005) is maintained at a constant or close to constanttemperature.

FIG. 20 shows a second embodiment of a heat and mass transfer device(2100) that has distinct and concentric heat transfer conduits (2001)and mass transfer conduits (2002). In this embodiment, the heat transferconduits (2001) are concentric and internal to larger diameter masstransfer conduits (2002). The mass transfer conduits (2002) are retainedby and sealed against two mass transfer manifold plates (2012). Longerheat transfer conduits (2001) are retained by and sealed against twoheat transfer manifold plates (2011). This arrangement leaves a gapbetween the outer diameter of the mass transfer conduits (2002) and theinner diameter of the heat transfer conduits (2001) into which theliquid desiccant may flow when introduced between the heat transfermanifold plate (2011) and the mass transfer manifold plate (2012). Theair to be dehumidified (2005) passes perpendicular to the axis of themass transfer conduits (2002). Dehumidified air (2006) exits the deviceafter it passes by the plurality of mass transfer conduits (2002). Aswater vapor in the air (2005) is absorbed by the liquid desiccant(2004), the temperature of the liquid desiccant (2004) in the masstransfer conduits (2002) tends to increase. A coolant (2003) isintroduced into the smaller, interior heat transfer conduits (2001),which reduces the magnitude of temperature increase of the liquiddesiccant (2004), with which it is in thermal contact. The heat transferconduits (2001) may be made entirely of a compatible material, notsubject to corrosion by the liquid desiccant (2004), or they may beconstructed from Aluminum or another material with high thermalconductivity, and then coated with a suitable barrier including PP, PPS,PVC, PTFE, and PVDF, among others. In either case, thin-walled tubing isdesirable for improved heat transfer from the liquid desiccant (2004) tothe coolant (2003). Other methods to increase heat transfer may also beused, such as fins, wall corrugations and features that increase fluidturbulence and heat transfer area.

As shown in FIGS. 21-24, some embodiments of the dehumidifying heatexchanger system include a liquid desiccant pump (2015) placeddownstream from the dehumidifying heat exchanger. This placement ensuresa lower liquid desiccant pressure as compared to the air to bedehumidified. Use of this approach reduces the likelihood of liquiddesiccant leaks, even in the event of abrasive damage, pinholes or otherimperfections of the microporous or solid electrolyte membrane of themass transfer conduits.

The mass transfer conduits in this section, and throughout thespecification, may be produced using various materials and methods thatachieve the desired water vapor transport from the humid air to theliquid desiccant and provide chemical compatibility with the liquiddesiccant. FIG. 25 shows a cross-sectional view that describes anembodiment of the mass transfer tube (2002). In order to contain theliquid desiccant in the mass transfer tube (2002), a hydrophobic andmicroporous membrane (2021) with porosity including, but not limited toa range of 0.05 microns to 0.5 microns, may be used. The combination ofsmall pores and a hydrophobic material prevents water from wickingthrough the microporous membrane under normal operating conditions(e.g., pressures under 20 psi). However, when the pressure inside thetube is increased above a breakthrough pressure liquid water can seepthrough the pore structure.

As used herein, “breakthrough pressure” relates to the minimum pressureat which liquid water will cross a hydrophobic microporous membrane thatis only water-vapor permeable at lower pressures. For example, thebreakthrough pressure of a hydrophobic sintered material with a porosityof 0.1 microns may be approximately 60 psi.

When operated at a breakthrough pressure, water will pass through to thesurface of the hydrophobic, microporous material to produce a thin sheetof water around the surface. An alternate technique for producing a thinsheet of water on the surface of the ducts is utilizing a hydrophilic,microporous material under lower pressures. Mister spray-heads can beused to introduce water droplets for evaporative cooling anywhere hereinwhere a hydrophobic, microporous material at a breakthrough pressure ora hydrophilic, microporous material is used. FIG. 33 shows an example ofa mister configuration.

To promote water vapor transport, in some embodiments, a thickness ofthe microporous membrane (2021) includes, but is not limited to therange of 10 microns to 50 microns and its open area should exceed 50%.In one embodiment, the open area is greater than 70%. For the purpose ofmechanically supporting this thin, microporous membrane, and to prohibitthe collapse of the membrane tube in the case that the liquid desiccantis at a lower pressure than the surrounding ambient air, a structural,internal support tube (2020) can be provided. This design approach, withthe microporous membrane (2021) covering the outside surface of thestructural support tube (2020), permits the liquid desiccant to benearest to the passing air to be dehumidified, and promotes water vaportransport across the membrane (2021). Both the structural tube (2020)and membrane (2021) may be produced from a suitable material such asPVDF, PP, PES, PPS, PVC, PTFE, and other suitable materials. Examples ofmass transfer conduits include micro- and ultra-filtration conduitsinclude those produced by Berghof from PES and PVDF membranes applied tosingle and dual layer supports.

Another example includes FIG. 26, which shows a product from Porex,which is an assembly of multiple filtration conduits housed in a largercylindrical vessel and is used for solids removal from water at elevatedpressures. These commercial filtration conduits are produced from PVDF,PE and PES and employ microporous membranes with porosity in the rangeof 0.05 microns to 0.5 microns, which are applied to porous substrateswith porosity in the range of 10 microns to 100 microns. Wall thicknessof the tubular substrate can be ranges that include, but are not limitedto 0.005″ to 0.050″, The placement of the microporous membrane can be onthe outside surface of the tubular substrate.

In a second embodiment of the mass transfer tube (2002), a structural,porous tube (2020) is again used as a substrate, onto which a solidelectrolyte membrane (2021) is applied. The porous substrate (2020) caninclude a sintered material such as PTFE, PVDF, PP or other suitablematerial, with porosity including, but not limited to the range of 10microns to 500 microns. The electrolyte membrane (2021), whichselectively transports water and not gases, is applied onto the outersurface of the substrate tube (2020) through spraying, dipping or otherdeposition methods. In some embodiments, a thickness of the electrolytemembrane (2021) is in a range that includes, but is not limited to 10microns to 100 microns. A wall thickness range of the structural poroussubstrate tube (2020) includes, but is not limited to 0.005″ to 0.050″.In some embodiments, the porous substrate tube (2020) is formed ofhydrophilic materials, in order to promote transfer of water through thesintered material and to the surface of the microporous membrane.

In a third embodiment of the mass transfer tube (2002), a structuralporous or perforated tube (2020) is used as a mechanical support, ontowhich a microporous membrane (2021) or an aforementioned solidelectrolyte membrane (2021) is attached. A porous tube (2020) may beproduced from sintered PVDF, PP or other suitable material with porosityin the range that includes, but is not limited to 10 microns to 500microns. A perforated tube (2020) with porosity in the range thatincludes, but is not limited to 0.05″ to 0.5″ may be produced byinjection or compression molding PP, PVDF, or other suitable material.The structural tube (2020) may have circular cross section, or it mayuse a foil-shape or other combination of circular and angular sectionsthat result in improved air flow directed perpendicular to its axis(FIG. 27). Certain cross sections, such as the foil-shape will enableassembly of the porous and perforated structures (2020) and membranes(2021) from sheet materials, bonded at the trailing edge using heatstaking, chemical adhesives and other methods known to one versed in theart.

One application for the dehumidifying heat exchanger is theaforementioned removal of latent heat from an air stream. A secondapplication for the liquid desiccant regeneration system describedherein is the removal of sensible heat from an air stream—the secondstage in producing dry, cool air for building air conditioning andrefrigeration. FIGS. 28, 29, 30, and 31 describe this two-stage airconditioning process to produce dry, cool air using two consecutive heatand mass transfer devices (2100), respectively. As it relates to FIGS.28-31, cooling of a dehumidified air stream (2006) may be accomplishedwithout increasing its humidity through heat exchange with a secondaryair stream (2009) whose temperature is reduced by evaporative coolingwith water (2008). The heat and mass transfer device (2100) of designshown in FIGS. 19a, 19b , or FIG. 20 may be used for this purpose bysubstituting water (2008) for the liquid desiccant (2004). In thissecond application, the dehumidified process air stream (2006) isintroduced into heat transfer conduits (2001) that exchange heat only(not water). Ambient air (e.g., return air (2009) from the building) isdirected across the mass transfer conduits (2002) where it picks upwater vapor and experiences a reduction in temperature due toevaporative cooling. This cooled air (2009) then exchanges heat directlywith the air in the heat transfer conduits (2001) when using the designof FIG. 19, or with the subsequent mass transfer conduits (2002), whenusing the design of FIG. 20, which in turn exchange heat with theinternal, concentric heat transfer conduits (2001). Dry, cool air (2007)is produced as a result of consecutively passing humid, hot air (2005)through two of the heat and mass transfer devices (2100); one configuredfor dehumidification of humid air (2005), and the second configured forhumidification and cooling of a secondary air stream (2009).

In one variation, chilled water or refrigerant from a vapor compressioncycle is introduced into the heat transfer conduits (2001) of thedehumidifying heat and mass transfer device. The chilled water orrefrigerant serves as the coolant (2003), which exchanges heat with theliquid desiccant (2004) as in earlier embodiments. Depending on coolant(2003) temperature and flow rate, the liquid desiccant (2004) may bemaintained at or reduced from its inlet temperature, further promotingdehumidification of the process air (2005) and potentially achieving thedesired building process air temperature without the use of a secondindirect cooling device.

FIG. 21 shows the implementation of the heat and mass transfer devices(2100) in an air conditioning system (2200) that is fueled with naturalgas, provides dry, cool air, and produces electricity as a by-product.Heat from a fuel cell is used to regenerate the liquid desiccant (2004)by liberating the water absorbed in the dehumidifying heat and masstransfer device (2100). This dry air (2006) is subsequently introducedinto the heat transfer conduits (2001) of a second heat and masstransfer device (2100), where it is indirectly cooled by a secondary airstream (2009) that is undergoing evaporative cooling.

In some embodiments, a heat and mass transfer device 2100 is described.The heat and mass transfer device can include a heat transfer ductsystem 2102, a mass transfer duct system 2104, and an air transport duct2106. As best shown in FIGS. 19, 20 & 28-31, portions of the heattransfer duct system 2102 and the mass transfer duct system 2104 extendthrough the air transport duct 2106. The mass transfer duct system 2104comprises a water vapor permeable wall 2108. As used herein, “watervapor permeable” refers to a material that is permeable to water vapor,but does not allow the transport of water from one side of the material(wall, membrane, etc.) to the other under standard pressures. Forexample, “water vapor permeable” membranes include microporous,hydrophobic materials.

In some embodiments, the heat transfer duct system 2102 includes aplurality of heat transfer ducts 2110 in fluid communication with a heattransfer fluid header chamber 2112 on one end and a heat transfer fluidexhaust chamber 2114 at an opposite end of the heat transfer ducts 2110.In some embodiments, the heat transfer ducts 2110 can be heat transferconduits 2001 having a cylindrical cross-section. In some embodiments,the individual heat transfer ducts 2110 can be parallel to one another.In some embodiments, the flow through the air transport duct 2106 can beperpendicular to the flow through the heat transfer ducts 2110. Althoughreferred to as “heat transfer fluid,” it should be understood that in aclosed cycle the heat transfer fluid will be relatively cold in someportions of the system (such as prior to cooling ambient air in an airconditioner), and warm in other portions of the system (after coolingthe ambient air in an air conditioner). As used herein, “warm” is usedto refer to temperatures at or above room temperature, for example, atleast 25° C., or at least 30° C., while “cool” is used to refer totemperatures below room temperature, for example, below 20° C., or below15° C.

In some embodiments, the mass transfer duct system 2104 includes aplurality of mass transfer ducts 2116 in fluid communication with adesiccant header chamber 2118 on one end and a desiccant exhaust chamber2120 at an opposite end of the mass transfer ducts 2116. In someembodiments, the mass transfer ducts 2116 can be mass transfer conduits2002 having a round cross-section. In some embodiments, the individualmass transfer ducts 2116 can be parallel to one another. In someembodiments, the flow through the air transport duct 2106 can beperpendicular to the flow through the mass transfer ducts 2116.

In some embodiments, such as those shown in FIGS. 19a & 19 b, theplurality of mass transfer ducts 2116 are spaced apart from andinterspersed with the plurality of heat transfer ducts 2110. As usedherein, “interspersed with” is used to refer to arrangements where theducts are independently placed and separated, but located in the sameregion, as shown in FIGS. 19a and 19b . The phrase “interspersed with”is intended to distinguish from arrangements where one duct is withinanother duct, as shown in FIG. 20.

As shown in FIG. 20, in some embodiments, each heat transfer duct 2110is positioned within a mass transfer duct 2116. The mass transfer ducts2116 are can be spaced apart from one another in some embodiments. Insome embodiments, one heat transfer duct 2110 is positioned coaxiallywithin each mass transfer duct 2116.

In some embodiments, the walls of the heat transfer ducts 2110 comprisea material selected from the group consisting of polyvinylidenedifluoride (PVDF), polypropylene (PP), polyvinyl chloride (PVC),polyphenylene sulfide (PPS), polyethersulfone (PES),polytetrafluoroethylene (PTFE), and combinations thereof.

In some embodiments, the walls of the heat transfer ducts 2110 do notcontain metal. This can be advantageous in embodiments where the heattransfer duct 2110 is within the mass transfer duct 2116, because suchembodiments can expose the exterior wall of the heat transfer duct 2110to a liquid desiccant flowing within the mass transfer duct 2116. Insome embodiments, the wall of the heat transfer duct can be formed of ametal coated with a non-corrosive coating, e.g., polyvinylidenedifluoride (PVDF), polypropylene (PP), polyvinyl chloride (PVC),polyphenylene sulfide (PPS), polyethersulfone (PES),polytetrafluoroethylene (PTFE), and combinations thereof.

As shown in FIGS. 19-33, in some embodiments, each heat transfer duct2110 is longer than each mass transfer duct 2116. In some embodiments,the heat transfer ducts 2110 are the same length. In some embodiments,the mass transfer ducts 2116 are the same length.

As best shown in FIG. 19b , in some embodiments, a first end of eachheat transfer duct 2110 is mounted to an opening 2122 in a heat transferheader plate 2124, and an opposite end of each heat transfer duct 2110is mounted to an opening 2126 in a heat transfer exhaust plate 2128. Insome embodiments, a first end of each mass transfer duct 2116 is mountedto an opening 2130 in a mass transfer header plate 2132, and an oppositeend of each mass transfer duct 2116 is mounted to an opening 2134 in amass transfer exhaust plate 2136.

As shown in FIG. 19b , in embodiments where the flow within the masstransfer ducts 2116 is counter to the flow within the heat transferducts 2110, at least a portion of the desiccant header chamber 2118 canbe between the heat transfer exhaust plate 2128 and the mass transferheader plate 2132. In such embodiments, at least a portion of thedesiccant exhaust chamber 2120 is between the heat transfer header plate2124 and the mass transfer exhaust plate 2136.

Although not shown, it will be easily understood that, in embodimentswhere the flow within the mass transfer ducts 2116 is in the samedirection as the flow within the heat transfer ducts 2110, at least aportion of the desiccant header chamber 2118 is between the heattransfer header plate 2124 and the mass transfer header plate 2132. Insuch embodiments, at least a portion of the desiccant exhaust chamber2120 is between the heat transfer exhaust plate 2128 and the masstransfer exhaust plate 2136.

In some embodiments, no mass exchange occurs between the heat transferduct system 2102 and the mass transfer duct system 2104. In someembodiments, the ducts 2110, 2116 can be attached to the respectiveheader plate 2124, 2132 and/or exhaust plate 2128, 2136 in a manner thatprevents leaks from one side of the plate 2124, 2128, 2132, 2136 to theother. Examples of techniques that can be used to produce such sealsinclude, but are not limited to, (a) compression forces transferredthrough an elastomer o-ring, (b) welding, (c) screwed on fastening, (d)chemical bonding, and (e) combinations thereof. As is evident from FIGS.19a, 19b , in some embodiments, the heat transfer ducts 2110 mustinteract with openings in the mass transfer plates 2132, 2136 to form aliquid tight seal in order to prevent fouling of the heat transfer fluidstream and the liquid desiccant stream.

In some embodiments, each mass transfer duct 2116 is longer than eachheat transfer duct 2110. Such embodiments are identical to those shownin FIGS. 19a, 19b , and 20, with the exception that heat transfer fluidis fed to the mass transfer ducts 2116 and the liquid desiccant is fedto the heat transfer duct 2110.

In some embodiments, the mass transfer duct system 2104 comprises walls2019 formed from a water vapor permeable material. In some embodiments,the wall(s) 2019 can include a porous support material 2020 (e.g., ascaffolding, such as that shown in FIGS. 25 & 27) and a water vaporpermeable material 2021. Examples of wall 2019 materials are thoseselected from the group consisting of a microporous plastic, structuralporous duct 2020 covered with a microporous plastic 2021, a structuralporous duct 2020 covered with a water-permeable, microporous polymerelectrolyte membrane 2021, or a combination thereof. As used herein,“covered” includes, but is not limited to, instances where a material iscoated onto a substrate and instances where a material (such as a film)is wrapped over or shrink wrapped onto the substrate. An example of aporous support material 2020 is shown in FIG. 27.

In some embodiments, the contents of the heat transfer duct system 2102are in thermal communication with contents of the air transport duct2106 via a wall 2103. The wall 2103 can include a material selected fromthe group consisting of polyvinylidene difluoride (PVDF), polypropylene(PP), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC),polyphenylene sulfide (PPS), polyethersulfone (PES), metal, andcombinations thereof. In some embodiments, the wall can be formed of ametal coated by polyvinylidene difluoride (PVDF), polypropylene (PP),polytetrafluoroethylene (PTFE), or combinations thereof. In otherembodiments, the wall can be formed of polyvinylidene difluoride (PVDF),polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinyl chloride(PVC), polyphenylene sulfide (PPS), polyethersulfone (PES), orcombinations thereof. Examples of metal that can be useful include, butare not limited to, titanium, stainless steel, and other corrosionresistant metals or alloys.

In some embodiments, a heat transfer fluid stream 2003 is fed into aninlet 2102 _(IN) of the heat transfer duct system 2102. In someembodiments, the heat transfer fluid stream comprises a heat transferfluid selected from a group that includes, but is not limited to, air,ethylene glycol, water, ammonia, fluorocarbons, chlorofluorocarbons,sulfur dioxide, halons, hydrocarbons, and mixtures thereof. As usedherein, “halons” has its standard meaning and includes haloalkanes.

In some embodiments, a liquid desiccant stream 2004 is fed into an inlet2104 _(IN) of mass transfer duct system 2104. In some embodiments, adesiccant (e.g., salt) concentration of the liquid desiccant stream 2004is lower at an outlet 2104 _(OUT) of the mass transfer duct system 2104than at the inlet 2104 _(IN) of the mass transfer duct system 2104.

In some system embodiments, such as those shown in FIGS. 21-24 and28-32, an air conditioning system 2200 that includes a first heat andmass transfer device 2100 _(A) and a second heat and mass transferdevice 2100 _(B) and any variants thereof described herein, isdescribed. In some embodiments of the air conditioning system 2200, anexhaust of the first air transport duct 2106 _(A,OUT) is in fluidcommunication with an inlet to the second heat transfer duct system 2102_(B,IN) For clarity, the subscript A will be used to refer to featuresof the first heat and mass transfer device 2100 _(A), while thesubscript B will be used to refer to features of the second heat andmass transfer device 2100 _(B), and the subscript C to refer to featuresof the third heat and mass transfer device 2100 _(C).

In some embodiments, air 2009 flowing through the second air transportduct 2106 _(B) is humidified by a liquid stream 2008 flowing in thesecond mass transfer duct 2102 _(B).

In some air conditioning system embodiments:

-   -   a first heat transfer fluid stream is fed into the first heat        transfer duct system 2102 _(A), 2112 _(A);    -   a high concentration liquid desiccant stream is fed into the        first mass transfer duct system 2104 _(A), 2118 _(A);    -   air being conditioned is fed into the first air transport duct        2106 _(A);    -   dehumidified air exiting the first air transport duct 2106 _(A)        is fed into the second heat transfer duct system 2102 _(B), 2112        _(B);    -   water is fed into the second mass transfer duct system 2104        _(B), 2118 _(B); and    -   secondary air 2009 is fed into the second air transport duct        2106 _(B).

In such embodiments, the second mass transfer duct system 2104 _(B) caninclude a wall (e.g., walls of the mass transfer ducts 2116 _(B))comprising a mass transfer membrane that is selectively permeable towater vapor. In such embodiments, the secondary air 2009 is humidifiedby water passing through the mass transfer membrane of the mass transferducts 2116 _(B) to produce humidified process air 2010. In suchembodiments, the mass transfer ducts 2116 _(B) can be formed of awater-vapor permeable membrane and operated at a pressure above thebreakthrough pressure of water-vapor permeable membrane, or the masstransfer ducts 2116 _(B) can be formed of a water permeable, microporousmaterial. In either case, a thin film of water can be produced on theexterior of the mass transfer ducts 2116 _(B) in order to facilitatehumidification of the secondary air 2009.

In some embodiments, the first heat transfer fluid stream 2003 comprisesair and the second heat transfer fluid stream comprises air 2009 thatundergoes evaporative cooling with water 2008 that sheets over thesurface of the mass transfer ducts 2116 _(B). In some embodiments, themass transfer ducts 2116B can have water permeable, microporous walls.In other embodiments, the mass transfer ducts 2116B can have wallsformed from water vapor permeable walls and the water pressure can be ator above the breakthrough pressure. In some embodiments, an exhauststream from the second heat transfer duct system 2102 _(B), 2114 _(B)comprises dehumidified, cooled air 2007 that is supplied to a spacebeing air conditioned. Examples of such embodiments are shown in FIGS.21-24 & 32.

In some embodiments, a low concentration liquid desiccant stream exitingthe first mass transfer duct system 2104 _(A,OUT), 2120 _(A) isregenerated to produce a high concentration liquid desiccant stream fedinto an inlet of the first mass transfer duct system 2104 _(A,IN), 2118_(A).

In some embodiments, the air conditioning system 2200 includes a fuelcell 2138. In some embodiments, the heat (e.g., from the coolant used inthe fuel cell) produced by the fuel cell 2138 is used to regenerate theliquid desiccant stream by driving water out of the liquid desiccantstream and produce a high concentration liquid desiccant stream.Examples of such embodiments are shown in FIGS. 21-24 & 32.

In some embodiments, such as those shown in FIGS. 21-24 & 32, the airconditioning system 2200 includes a regeneration system 2140. In someembodiments, such as the one shown in FIG. 21, the regeneration systemrelies upon a counter-flow heat exchanger 2145. In some embodiments,warm heat transfer fluid (e.g., hot water) from the fuel cell 2138 isfed into the heat transfer line inlet 2152 of the heat exchanger 2145and the heat transfer fluid exiting the heat transfer line outlet 2154is returned to the fuel cell 2138. A low concentration liquid desiccantstream from the desiccant exhaust chamber 2120A can be fed into a heatexchanger desiccant inlet 2156 of the heat exchanger 2145. Thelow-concentration liquid desiccant is heated as is passes through theheat exchanger 2145. The low-concentration liquid desiccant exiting theheat exchanger desiccant outlet 2158 then proceeds to a mass transferunit 2150.

The low-concentration liquid desiccant from the heat exchanger desiccantoutlet 2158 enters the mass transfer unit 2150 through the mass transferdesiccant inlet 2160 then flows through the mass transfer desiccantducts 2161 before exiting the mass transfer desiccant outlet 2162. Thefuel cell exhaust 2163 is fed into the mass transfer heating inlet 2164,passes through a mass transfer heating ducts 2165 and exits the masstransfer heating outlet 2166. Water in the liquid desiccant stream whichwas previously heated in the heat exchanger 2145 is driven out of themass transfer desiccant ducts 2161 in the form of water vapor. In someembodiments, the mass transfer desiccant ducts 2161 have water vaporpermeable, microporous walls to drive water out of the low-concentrationliquid desiccant and produce a high concentration liquid desiccantstream exiting the mass transfer desiccant outlet 2162.

The high-concentration liquid desiccant stream exiting the mass transferdesiccant outlet 2162 can then be fed into a radiator 2168 for cooling.The high concentration liquid desiccant stream can then be fed into thedesiccant header chamber 2118 _(A) of the first heat and mass transferdevice 2100 _(A).

In other embodiments, such as those shown in FIGS. 22-24 & 32, theregeneration system 2140 can include a moisture removal duct 2106C, anda desiccant regeneration duct 2116C that extends through the moistureremoval duct 2106C, wherein water vapor from the liquid desiccant streamin the desiccant regeneration duct 2116C selectively passes through adesiccant regeneration duct membrane forming the wall of the duct 2116Cand into the moisture removal duct 2106C where it is entrained in thehumidified air 2011. In some embodiments, such as those shown in FIGS.22-24, warm coolant from the fuel cell 2138 heats the liquid desiccantstream thereby driving water from the liquid desiccant stream in themass transfer ducts 2116C into the removal stream passing through themoisture removal duct 2106C. The high humidity water recovery stream2011 can be fed into a radiator to precipitate and capture the moisturein the water recovery stream 2011.

In some embodiments, the regeneration system 2140 includes a thirdheat/mass transfer device 2100C as described herein. In suchembodiments, an outlet 2120A of the first mass transfer duct system2104A is in fluid communication with an inlet 2118C of the third masstransfer duct system 2104C, and an outlet 2120C of the third masstransfer duct system 2104C is in fluid communication with an inlet 2118Aof the first mass transfer duct system 2104A. In some embodiments, thewarm exhaust from the fuel cell 2138 is fed into an inlet of the thirdair transport duct 2106C, and warm heat transfer fluid (e.g., hot water)from the fuel cell 2138 is fed into an inlet 2112C of the third heattransfer duct system 2102C. Examples of such embodiments are shown inFIGS. 22-24 & 32.

As shown in FIGS. 22-24 & 32, the high concentration liquid desiccantexiting the third desiccant exhaust chamber 2120C is then fed into aheat exchanger intended to cool the high concentration liquid desiccantstream before it is fed into the first desiccant header chamber 2118A.In FIGS. 22-24, the heat exchanger is a radiator used using a fan andambient air to cool the cooled, humidified fuel cell exhaust streamexiting the third air transport duct 2106C and the high concentrationliquid desiccant exiting the third desiccant exhaust chamber 2120C. InFIG. 32, the heat exchanger is a fourth heat and mass exchange unit2100D that has been modified to use impermeable mass transfer ducts2116D, so that there is no mass exchange Rather, the air flowing throughthe air transport duct 2106D is used to cool both the humid fuel cellexhaust stream flowing through the heat transfer ducts 2110D and thehigh-concentration liquid desiccant stream in the mass transfer ducts2116D (which have been modified so they are not mass transfer ducts).

A first specific heat and mass transfer device can include a heattransfer duct system; a mass transfer duct system; and an air transportduct, wherein portions of said heat transfer duct system and said masstransfer duct system extend through said air transport duct, wherein themass transfer duct system comprises a water vapor permeable wall.

A second HMX device includes the first HMX device wherein said heattransfer duct system comprises a plurality of heat transfer ducts influid communication with a heat transfer fluid header chamber on one endand a heat transfer fluid exhaust chamber at an opposite end of the heattransfer ducts.

A third HMX device includes any of the foregoing HMX devices, whereinthe mass transfer duct system comprises a plurality of mass transferducts in fluid communications with a desiccant header chamber on one endand a desiccant exhaust chamber at an opposite end of the mass transferducts.

A fourth HMX device includes the third HMX device, wherein said heattransfer duct system comprises a plurality of heat transfer ducts influid communication with a heat transfer fluid header chamber on one endand a heat transfer fluid exhaust chamber at an opposite end of the heattransfer ducts.

A fifth HMX device includes the fourth HMX device, wherein saidplurality of mass transfer ducts are spaced apart from and interspersedwith and said plurality of heat transfer ducts.

A sixth HMX device includes the fourth HMX device, wherein each heattransfer duct is positioned within a mass transfer duct, and whereinsaid mass transfer ducts are spaced apart from one another.

A seventh HMX device includes the sixth HMX device, wherein one heattransfer duct is positioned coaxially within each mass transfer duct.

A eighth HMX device includes the sixth HMX device, wherein walls of saidheat transfer ducts comprise a material selected from the groupconsisting of polyvinylidene difluoride (PVDF), polypropylene (PP),polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyethersulfone(PES), polytetrafluoroethylene (PTFE), and combinations thereof.

A ninth HMX device includes the fourth HMX device, wherein each heattransfer duct is longer than each mass transfer duct.

A tenth HMX device includes the ninth HMX device, wherein a first end ofeach heat transfer duct is mounted to an opening in a heat transferheader plate, and an opposite end of each heat transfer duct is mountedto an opening in a heat transfer exhaust plate; wherein a first end ofeach mass transfer duct is mounted to an opening in a mass transferheader plate, and an opposite end of each mass transfer duct is mountedto an opening in a mass transfer exhaust plate; wherein at least aportion of said desiccant header chamber is between said heat transferheader plate and said mass transfer header plate; and wherein at least aportion of said desiccant exhaust chamber is between said heat transferexhaust plate and said mass transfer exhaust plate.

A eleventh HMX device includes the fourth HMX device, wherein each masstransfer duct is longer than each heat transfer duct.

A twelfth HMX device includes any of the foregoing HMX devices, whereinno mass exchange occurs between said heat transfer duct system and saidmass transfer duct system.

A thirteenth HMX device includes any of the foregoing HMX devices,wherein said mass transfer duct system comprises a wall formed from amaterial selected from the group consisting of a microporous plastic,structural porous duct covered with a microporous plastic, a structuralporous duct covered with a water permeable polymer electrolyte membrane,or a combination thereof.

A fourteenth HMX device includes any of the foregoing HMX devices,wherein contents of the heat transfer duct system are in thermalcommunication with contents of the air transport duct via a wall,wherein said wall comprises a material selected from the groupconsisting of polyvinylidene difluoride (PVDF), polypropylene (PP),polyvinyl chloride (PVC), polyphenylene sulfide (PPS),polytetrafluoroethylene (PTFE), metal, and combinations thereof.

A fifteenth HMX device includes any of the foregoing HMX devices,wherein an inlet of said heat transfer duct is in fluid communicationwith a heat transfer fluid stream.

A sixteenth HMX device includes the fifteenth HMX device, wherein theheat transfer fluid stream comprises a heat transfer fluid selected fromthe group consisting of air, ethylene glycol, propylene glycol,glycerol, water, ammonia, fluorocarbons, chlorofluorocarbons, sulfurdioxide, halons, hydrocarbons, and mixtures thereof.

A seventeenth HMX device includes any of the foregoing HMX devices,wherein a liquid desiccant stream is fed into an inlet of said masstransfer duct system.

An eighteenth HMX device includes the seventeenth HMX device, wherein adesiccant concentration of the liquid desiccant stream is lower at anexit of the mass transfer duct system than at the inlet of the masstransfer duct system.

A first air conditioning system includes first and second HMX devicesaccording to any of the foregoing HMX devices, wherein an exhaust of thefirst air transport duct is in fluid communication with an inlet to thesecond heat transfer duct system.

A second air conditioning system that includes the first airconditioning system, wherein air flowing through the second airtransport duct undergoes evaporative cooling by a liquid streamcontaining water flowing in the mass transfer duct.

A third air conditioning system that includes any of the foregoing airconditioning systems, wherein:

-   -   a first heat transfer fluid stream is fed into the first heat        transfer duct system;    -   a high concentration liquid desiccant stream is fed into the        first mass transfer duct system;    -   air being conditioned is fed into the first air transport duct;    -   dehumidified air exiting the first air transport duct is fed        into the second heat transfer duct system;    -   a stream containing water is fed into the second mass transfer        duct system; and    -   secondary air is fed into the second air transport duct,

wherein the second mass transfer duct system comprises a wall comprisinga mass transfer membrane that allows liquid water to pass, and whereinsaid secondary air undergoes evaporative cooling by water passingthrough the mass transfer membrane.

A fourth air conditioning system that includes the third airconditioning system, wherein the first heat transfer fluid streamcomprises air.

A fifth air conditioning system that includes any of the foregoing airconditioning systems, wherein an exhaust stream from the second heattransfer duct system comprises dehumidified, cooled air that is suppliedto a space being air conditioned.

A sixth air conditioning system that includes any of the foregoing airconditioning systems, wherein a low concentration liquid desiccantstream exiting said first mass transfer duct system is regenerated toproduce a high concentration liquid desiccant stream fed into an inletof the first mass transfer duct system.

A seventh air conditioning system that includes any of the foregoing airconditioning systems, further comprising a fuel cell, wherein warm heattransfer fluid from the fuel cell is used to regenerate the liquiddesiccant stream by driving water out of the liquid desiccant stream.

An eighth air conditioning system that includes the sixth airconditioning system, further comprising a regeneration system,comprising: a moisture removal duct; and a desiccant regeneration ductextends through said moisture removal duct, wherein water vapor from theliquid desiccant stream in said desiccant regeneration duct selectivelypasses through a desiccant regeneration duct membrane into the moistureremoval duct.

A ninth air conditioning system that includes the sixth air conditioningsystem, wherein warm heat transfer fluid from the fuel cell heats theliquid desiccant stream thereby driving water from the liquid desiccantstream into the fuel cell exhaust stream passing through the moistureremoval duct.

A tenth air conditioning system that includes the ninth air conditioningsystem, wherein the regeneration system comprises a third HMX deviceaccording to any of the foregoing specific HMX devices, wherein anoutlet of the first mass transfer duct system is in fluid communicationwith an inlet of the third mass transfer duct system, and an outlet ofthe third mass transfer duct system is in fluid communication with aninlet of the first mass transfer duct system.

An eleventh air conditioning system that includes the tenth airconditioning system, wherein the warm exhaust from the fuel cell is fedinto an inlet of the third air transport duct, and warm heat transferfluid from the fuel cell is fed into an inlet of the third heat transferduct system.

Fourth Discussion

Described herein are methods and designs for a system where the heatexhausted from an engine is used to heat a liquid desiccant and/or anair stream, the latter referred as carrier air in this document. Thecarrier air is heated so that the partial pressure of the water vaporcontained in the carrier air is lower than the concentration of water ina liquid desiccant stream that will be regenerated. The interactionbetween the liquid desiccant and the carrier air is accomplished througha membrane that is permeable to water vapor but not to the transfer ofliquids, such as the liquid desiccant or liquid water. Given thedifference in water concentration between the carrier air and the liquiddesiccant, water flows from the liquid desiccant to the carrier air inthe form of water vapor.

The process of liquid desiccant regeneration is continuously heated by ahot coolant stream proceeding from the engine that carries part or allof the heat produced by the engine. The hot coolant can in the form of agas or a liquid. In some embodiments, the coolant can be a phasechanging fluid in order to enhance heat transfer.

Desiccant regeneration occurs within a heat and mass transfer system(HMX) that enables heat transfer between the liquid desiccant, thecoolant, and the carrier gas. It also enables exchange of water vaporbetween the liquid desiccant and the carrier air. The HMX is composed ofa plurality of conduits over which carrier gas flows in a counterflow orcross flow manner. A certain group of the conduits flow liquid desiccantand another group of conduits flow coolant.

The outer wall of any of the conduits containing liquid desiccantdescribed herein can be made of a material that is hydrophobic,impermeable to liquids, and permeable to water vapor. Such materials canbe sulfonated tetrafluoroethylene based fluoropolymer-copolymer(Nafion™, sold by DuPont), water conducting fluoropolymers, andnon-fluorinated proton conducting polymers such as NanoClear™, availablefrom Dais Analytic, high density polyethelene, spunbond olefins, amongothers described herein. The conduits in which coolant flow continuouslywarm the air, maintaining its relative humidity low. The distribution ofthese conduits can be such that a greater concentration of conduitscarrying coolant occurs in the HMX area closer to the inlet of thecarrier air.

An alternative HMX design is one where there is a tube assembly composedof a tube or a plurality of conduits within a larger diameter tube. Inthis case coolant flows within the smaller diameter conduits in the tubeassembly and liquid desiccant flows within the larger diameter tube, butnot within the smaller diameter conduits. The wall of the inner, smallerdiameter conduits is made of a material that allows for heat transferbetween the coolant and the liquid desiccant, but does not allow formixing of the liquid desiccant with the coolant. These tube are made ofmaterials that are chemically compatible with the liquid desiccant. Theouter wall of the tube assembly is composed of a material that ispermeable to water vapor but not permeable to liquids. The HMX would becomposed of a plurality of these tube assemblies. Carrier air flowsaround these tube assemblies in crossflow. The liquid desiccant and thecoolant flow counter-flow with respect to each other.

There may be cases where the coolant flow is much higher than thecarrier air flow, or in which due to design or pressure dropconsiderations, it is convenient for the coolant to flow on the outsideof the HMX conduits or tube assemblies. In these cases, the HMX would becomposed of a chamber with a plurality of tube assemblies. These tubeassemblies would be composed of an outer tube in which one or moresmaller diameter conduits are located within These smaller diameterconduits flow carrier gas within them. The outer, larger diameter tubeflows liquid desiccant. The walls of the smaller diameter conduits aremade of a material that is permeable to water vapor but not permeable tothe flow of liquids. The wall of the outer, larger diameter tube is madeof a material that is chemically compatible with the liquid desiccantbut that is impermeable to gas or liquid. In this way, the liquiddesiccant and the coolant only have heat transfer interaction but nomixing occurs. This design is principally relevant for cases where thecoolant is a gas.

An alternative case may occur, where the coolant may be too hot to flownext to the liquid desiccant. In this case the HMX tube assemblies are,as previously described, made of a larger diameter tube within which isat least a single smaller diameter tube. The carrier air flows withinthe larger diameter tube but not within the smaller diameter conduits.The liquid desiccant flows within the smaller diameter conduits. Thewall of the smaller diameter tube is made of a material permeable towater vapor and not permeable to liquids. The wall of the outer diametertube is made of a material that prevents mixing between the hot coolantand the carrier air, but allows for heat transfer between the carrierair and the hot coolant. By heating the carrier air directly, andindirectly heating the liquid desiccant, the liquid desiccant stream canbe protected from elevated coolant temperatures that could lead tochemical deterioration of the liquid desiccant.

In order to maintain separation between the flows within the conduits,the HMX assembly uses headers. The HMX conduits have two distinctlengths. The different lengths enable introduction of liquid desiccantinto conduits of a certain length and either coolant or carrier air(depending on design as discussed in the paragraphs above) into conduitsof a different length. The header of the HMX has two chambers, oneadjacent the other. The header chamber closest to the interior portionof the HMX has fluid connection with the interior portion of the shorterlength conduits, but does not have fluid connection with the interiorportion of longer length conduits. The header chamber farthest from theinterior of the HMX is in fluid connection with the interior portion ofthe longer length conduits. The two header chambers are not in fluidconnection with each other.

In an alternative HMX design, where the tube-in-tube assemblies are notemployed, the header chambers are next to each other but not in fluidconnection with each other.

Heat and mass transfer enhancements can be made to the HMX. In the casethat the carrier air flows across the outside of the HMX conduits ortube assemblies, mass transfer between the air and the liquid desiccantcan be enhanced by placing walls in the HMX so that the carrier air hasto flow in a tortuous path. In this way the space velocity of thecarrier air in the HMX can be varied enhancing mass transfer.

An alternative method of enhancing mass and heat transfer in the HMXwould be through the addition of vertical features that block a portionof the carrier air flow through the HMX. In this way, vortices andturbulence can be accomplished. These features can be rods over whichthe carrier air must pass. The rods may have roughness or features toenhance the creation of vortices or turbulences. These features can alsobe used to create helical bulk flow of the carrier air through the HMXby acting as fins that direct flow.

The engine exhaust gas contains products of the oxidation of a fuel,which includes water. In the case the engine exhaust has a highertemperature than the carrier air entering the system, gas to gas heatexchanger is used to transfer heat from the engine exhaust to thecarrier air. The carrier air then enters into the HMX. The gas to gasheat exchanger can be made of plates with triangular or corrugatedsheets that form structural elements as well as flow channels. Thecorrugated sheets form channels that are perpendicular to the channelsin the adjacent plates. The direction of the corrugations also block airflow into certain plates. This ensures the engine exhaust gas does notmix with the carrier air in the gas to gas heat exchanger. Other methodsfor gas to gas heat exchange known in the art can also be used.

The carrier air leaving the HMX is mixed with the engine exhaust gasleaving the gas to gas heat exchanger. A mixer can be used to reduce thepressure drop associated with the integration of the two flows. Leavingthe mixer the combined gas is cooled in order to condense the air in theair stream. The condenser can use ambient air as the cooling fluid.Water condensed is collected in a water reservoir. The cool gas leavingthe condenser is exhausted.

Instances may exist where carrier air and engine exhaust gas mixing isnot practical due to flow rate disparity, pressure drop considerations,or chemical compatibility. In these cases, the carrier gas isindependently condensed through an independent condenser. The carriergas leaving the HMX also passes through an independent condenser. Thewater condensed from both the carrier air stream and from the engineexhaust gas is collected in a water reservoir.

The liquid desiccant, at a high concentration point, leaving the HMX isstored in a reservoir.

Compared to the state of the art, the systems described herein offermany advantages. For example, the liquid desiccant regeneration systemsnot only regenerates the liquid desiccant but it also collects waterproduced from the engine and the water removed from the liquid desiccantduring the regeneration process. Water recovery and accumulation ishighly valuable. If the engine exhaust stream and the carrier air streamis devoid of toxic substances, the water collected could be used forhuman, agricultural, or livestock processes. Water can also be used tosupport air conditioning operation. Water can also be used to supportengine processes, such as fuel processing or cooling.

The liquid desiccant regeneration systems described herein also preventsthe mixture of liquid desiccant with other streams. Liquid desiccantsare typically corrosive Maintaining the liquid desiccant separate fromother flows reduces the potential for corrosion of valves, tanks,ducting, etc.

The liquid desiccant regeneration systems will now be described moreparticularly, by way of example, with reference to the accompanyingdrawings, in which:

FIG. 34 shows an embodiment of a process diagram for the liquiddesiccant regeneration system. As shown, low concentration liquiddesiccant (3002) flows from a reservoir (3001) to the HMX (3015). TheHMX (3015) also receives a hot coolant stream (3006) leaving an engine(3005). Carrier air (3008) is introduced to the system and flows throughan air to air heat exchanger (3021) where it warmed. The warm carrierair (3009) is introduced into the HMX. The carrier air (3008) is warmedthrough heat exchange with engine exhaust (3013) leaving the engine(3005). Within the HMX (3015) the coolant provides the heat to supportthe transfer of water vapor from the liquid desiccant (3002) to the warmcarrier air (3009). The streams leaving the HMX (3015) is humidifiedcarrier air (3010), high concentration liquid desiccant (3003), andcoolant (3007). The coolant (3007) returns to the engine. The highconcentration liquid desiccant (3003) is stored in a reservoir (3004).Carrier air (3010) leaving the HMX (3015) is mixed with engine exhaust(3014) in a mixer (3016) designed to reduce pressure drop associatedwith the combination of the two streams. The combined flow (3011) iscooled in a condenser (3017) which is a heat exchanger cooled withoutside air (3018) or any other fluid that is at a lower temperaturethan the combined flow (3011) leaving the mixer. The cooling of thecombined flow (3011) condenses a portion of the water in the flow. Thiswater condensed (3019) is stored in a water reservoir (3020). Thecombined flow (3012) leaving the condenser is exhausted.

FIG. 35 shows the same process as described in FIG. 34, however in thiscase, the carrier air (3010) leaving the HMX (3015) is condensed in aseparate heat exchanger in the condenser (3017). The engine exhaust(3014) leaving the air to air heat exchanger (3021) is also condensed ina separate heat exchanger in the condenser (3017). Each gas streamleaving the condenser (3017) has its own exhaust (3012 and 3013).

FIG. 36 shows an embodiment of the design of the HMX (3015). The figureshows the internal portion of the HMX (3150) and its internal walls, inorder to show its general geometry and construction. Carrier air (3009)enters the HMX (3015) and flow around conduits carrying coolant (3027)and conduits carrying liquid desiccant (3028). The walls of the conduitscarrying liquid desiccant (3028) are made of material that ishydrophobic, permeable to water vapor, but not permeable to liquids. Theconduits carrying coolant (3027) are longer than the conduits carryingliquid desiccant (3028). The liquid desiccant tube ends are sealed andattached to plates (3032 a and 3032 b) at each end. The ends of theconduits carrying coolant (3027) are sealed and attached to plates (3031a and 3031 b). The different tube lengths form separate spaces (3022 a,3022 b, 3023 a and 3023 b) where liquid desiccant (3003) and coolant(3006) can be introduced into the HMX (3015).

FIG. 37 shows the HMX (3015) design using tube assemblies (3024). As inFIG. 36 carrier air (3009) flow across the tube assemblies (3024). Thetube assemblies (3024) are composed of two different diameter conduits,the smaller one inside the other. The smaller diameter tube is longerthan the larger diameter tube. The longer length tube is attached andsealed to the wall of the tube at its ends to two plates (3031 a and3031 b). Flow in and out of the tube is not restricted by the plates(3031 a and 3031 b). These plates (3031 a and 3031 b) form fluid barrierbetween the fluids entering and exiting the longer length tube in thetube assembly (3024). Plates (3032 a and 3032 b) are attached to theends of the shorter length tube in the tube assembly (3024) in such away that they seal the wall of the tube to the plates (3032 a and 3032b) but do not restrict flow in an out of the tube.

FIG. 38 shows in greater detail the construction of the tube assembly(3024) in an HMX in a cross-sectional cutout view of the HMX. Hotcoolant (3006) enters the HMX (3015) in the chamber (3022 a) created byan external header wall (3033 a) and the plate (3031 a) that is attachedto wall (3030) of the longer length conduits of the tube assembly(3024). The hot coolant is able to flow into the longer length tube ofthe tube assembly (3024) and exit into the chamber (3022 b) formed bythe space between an external header wall (3033 b) and the plate (3031b) attached to the tube wall (3030) at the other end of the longerlength tube in the tube assembly (3024). The coolant (3007) exits theHMX (3015) through the chamber (3022 b). FIG. 37 shows a top down flowof hot coolant (3006), however this is arbitrary. The coolant (3006)flow could be bottom to top in the HMX (3015). Also, the orientation ofthe HMX (3015) can be any which way better suits the use of the liquiddesiccant regeneration systems described herein for a certainapplication.

As shown in FIG. 38, the low concentration liquid desiccant (3002)enters the HMX (3015) in through the chamber (3023 b) opposite the entrychamber (3022 a) of the hot coolant (3006). The entry chamber (3023 b)of the low concentration liquid desiccant (3002) is bound by the plate(3031 b) attached to the wall (3030) at the end of the longer lengthtube of the tube assembly (3024) and the plate attached to the plate(3032 b) attached to the wall (3029) of the shorter length tube of thetube assembly (3024). Liquid desiccant (3002) is able to flow around theouter wall (3030) of the longer length tube of the plate assembly (3024)but there is no fluid connection between the liquid desiccant stream(3002 and 3003) and the coolant streams (3006 and 3007). The liquiddesiccant (3002) is able to flow in the annular space between the longerlength tube and the shorter length tube of the tube assembly (3024). Theouter wall (3029) of the shorter length tube of the tube assembly (3014)is entirely or partially composed of a hydrophobic material that ispermeable to water vapor but not to liquids. Carrier air (3009) thatenters the HMX (3015) picks up water vapor from the liquid desiccant(3002) as it flows around the tube assemblies (3024) in the HMX. Theliquid desiccant leaves the HMX (3015) through a chamber (3023 a) thatmaintains separated the liquid desiccant stream (3003) and the coolantstream (3006). A plurality of these tube assemblies (3024) exist in theHMX (3015).

FIG. 39 shows a cross-section top view of a tube assembly (3024).Carrier air (3009) flows around the tube assembly (3024). The outermostwall (3029) of the tube assembly is made of a hydrophobic materialpermeable to water vapor but not permeable to liquids. Liquid desiccant(3003) flows out of the page (shown with a period to represent this) andwithin the annular compartment made by the wall (3030) of the innermosttube of the tube assembly (3024) and the outermost wall of the tubeassembly (3029). Hot coolant (3006) flows into the page (shown as a plussign to represent this), so the liquid desiccant (3003) and the hotcoolant (3006) are in counterflow. The innermost wall (3030) of the tubeassembly (3024) is made of a material that completely seals the coolant(3006) from the liquid desiccant (3003), but allows heat transferbetween the two fluids.

FIG. 40 shows an alternative structure of the tube assembly (3024),where hot coolant (3006) flows across the outside of the tube assembly(3024). In this case outermost wall (3030) of the tube assembly (3024)is made of a material that allows heat transfer between the coolant(3006) and the liquid desiccant (3003). The liquid desiccant flowswithin the annular compartment bound by the outermost wall (3030) of thetube assembly (3024) and the innermost wall (3029) of the tube assembly.Carrier air (3009) flows within the innermost tube in the tube assembly(3024). The innermost wall (3029) of the tube assembly is made of ahydrophobic material that is permeable to water vapor but not toliquids.

FIG. 41 shows another alternative to the structure of the tube assembly(3024), where hot coolant (3006) flows across the outside of the tubeassembly (3024). In this case outermost wall (3030) of the tube assembly(3024) is made of a material that allows heat transfer between thecarrier air (3009) and the coolant (3006). The carrier air flows withinthe annular compartment bound by the outermost wall (3030) of the tubeassembly (3024) and the innermost wall (3029) of the tube assembly.Liquid desiccant (3003) flows within the innermost tube in the tubeassembly (3024). The innermost wall (3029) of the tube assembly is madeof a hydrophobic material that is permeable to water vapor but not toliquids.

FIG. 42A and FIG. 42B show the HMX (3015) with heat and mass transferenhancements between the carrier air (3009) and the tube assemblies(3024). Flow disrupters (3034) are place throughout the HMX in order tocreate turbulence and direct flow. The flow disrupters (3034) shown inthis embodiment are cylindrical rods placed so that they runperpendicular to the direction of the tube assemblies (3024).

FIG. 43 shows the HMX (3015) with structural elements that cause theflow of the carrier air (3009) to be sinusoidal throughout the HMX(3015). This increases reactor effective length.

A first liquid desiccant regeneration system can include a heat and massexchanger, comprising: a plurality of exchange components extendingacross a heat and mass exchanger duct, wherein a flow through said heatand mass exchanger duct is cross-flow relative to said exchangecomponents, wherein said exchange components comprise a plurality offirst elongated, hollow conduits and a plurality of second elongated,hollow conduit; and an engine producing an exhaust stream and a coolantstream, wherein said exhaust stream is in thermal communication with acarrier air stream subsequently fed into the heat and mass exchanger,wherein said heat and mass exchanger receives a liquid desiccant stream,the coolant stream, and a carrier air stream, wherein one of said firstand second elongated, hollow conduits comprises a water vapor permeabletube wall, and wherein the liquid desiccant stream and the carrier airstream are in contact with said water vapor permeable tube wall.

A second desiccant regeneration system according to the first desiccantregeneration system, wherein said each of said first and secondelongated, hollow conduits is spaced apart from the other.

A third desiccant regeneration system according to the second desiccantregeneration system, wherein said first elongated, hollow conduitsextend laterally across said heat and mass exchanger duct and saidsecond elongated, hollow conduits extend transverse to said firstelongated, hollow conduits.

A fourth desiccant regeneration system according to the second desiccantregeneration system, wherein each of said first elongated, hollowconduits is an outer conduit of a tube-in-tube exchanger component, eachof said tube-in-tube exchanger components further comprising an innerconduit, wherein an inner lumen is defined by said inner conduit and anouter flow channel is external to said inner conduit and adjacent a wallof said second elongated, hollow conduit.

A fifth desiccant regeneration system according to any of the foregoingdesiccant regeneration systems, wherein said exchange componentscomprise tube-in-tube exchange components, wherein each tube-in-tubecomponents comprises one first elongated, hollow conduit within onesecond elongated, hollow conduit, forming an inner lumen within saidfirst elongated, hollow conduit and an outer flow channel external tosaid first elongated, hollow conduit and adjacent a wall of said secondelongated, hollow conduit.

A sixth desiccant regeneration system according to the fifth desiccantregeneration system, wherein said coolant stream flows through saidcentral lumen, said liquid desiccant stream flows through said sheath,and said carrier air stream flows through said heat and mass exchangerduct.

A seventh desiccant regeneration system according to the sixth desiccantregeneration system, wherein the coolant stream and the liquid desiccantstream are configured in a counter flow arrangement.

A eighth desiccant regeneration system according to the fifth desiccantregeneration system, wherein said carrier air stream flows through saidcentral lumen, said liquid desiccant stream flows through said sheath,and said coolant stream flows through said heat and mass exchanger duct.

A ninth desiccant regeneration system according to the eighth desiccantregeneration system, wherein the carrier air stream and the liquiddesiccant stream are configured in a counter flow arrangement.

A tenth desiccant regeneration system according to the fifth desiccantregeneration system, wherein said liquid desiccant stream flows throughsaid central lumen, said carrier air stream flows through said sheath,and said coolant stream flows through said heat and mass exchanger duct.

An eleventh desiccant regeneration system according to the tenthdesiccant regeneration system, wherein the liquid desiccant stream andthe carrier air stream are configured in a counter flow arrangement.

A twelfth desiccant regeneration system according to any of theforegoing desiccant regeneration systems, wherein the carrier air streamexiting the heat and mass exchanger passes through a condenser, whereina water trap of said condenser is in fluid communication with areservoir.

A thirteenth desiccant regeneration system according to any of theforegoing desiccant regeneration systems, wherein, after thermallycontacting the carrier air stream, the exhaust stream passes through acondenser, wherein a water trap of said condenser is in fluidcommunication with a reservoir.

A fourteenth desiccant regeneration system according to the thirteenthdesiccant regeneration system, wherein, the carrier air stream exitingthe heat and mass exchanger is mixed with the exhaust stream to form acombined air stream and the combined air stream passes through acondenser.

A fifteenth desiccant regeneration system according to any of theforegoing desiccant regeneration systems, wherein a low concentrationliquid desiccant reservoir is in fluid communication with a highconcentration liquid desiccant reservoir via the liquid desiccantstream.

A sixteenth desiccant regeneration system according to any of theforegoing desiccant regeneration systems, wherein, after passing throughthe heat and mass exchanger, the coolant stream is reintroduced into theengine.

A seventeenth desiccant regeneration system according to any of theforegoing desiccant regeneration systems, further comprising a pluralityof flow disrupters extending from at least one wall of said heat andmass exchanger duct.

An eighteenth desiccant regeneration system according to the seventeenthdesiccant regeneration system, wherein the flow disrupters extend acrosssaid heat and mass exchanger duct.

A nineteenth desiccant regeneration system according to the seventeenthdesiccant regeneration system, wherein said flow disrupters have across-sectional shape selected from the group consisting of airfoils,triangles, rectangles, ovals, egg-shaped.

A twentieth desiccant regeneration system according to the seventeenthdesiccant regeneration system, wherein said heat and mass exchanger ductcomprises first and second longitudinal walls opposite one another, andsaid flow disrupters comprise at least one first fin extending from thefirst longitudinal wall partially across said heat and mass exchangerduct and at least one second fin extending from the second longitudinalwall partially across said heat and mass exchanger duct.

A twenty-first desiccant regeneration system according to the twentiethdesiccant regeneration system, wherein said flow disruptors cause flowthrough said heat and mass exchanger duct to travel in an s-shaped path.

A twenty-second desiccant regeneration system according to any of thefifth through twenty-first desiccant regeneration systems, wherein atleast one of said tube-in-tube exchange components comprises a flowdisrupter.

A twenty-third desiccant regeneration system according to any of theforegoing desiccant regeneration systems, wherein said exhaust stream iscontacted with said carrier air stream via a heat exchanger.

A twenty-fourth desiccant regeneration system according to any of thefifth through twenty-third desiccant regeneration systems, wherein eachof said tube-in-tube exchanger components further comprises anintermediate elongated, hollow conduit, wherein the outer flow channelis defined between an outer wall of said intermediate elongated, hollowconduit and said second elongated, hollow conduit, and an intermediateflow channel is defined between said first elongated, hollow conduit andsaid intermediate elongated, hollow conduit.

The foregoing is provided for purposes of illustrating, explaining, anddescribing embodiments of this invention. Modifications and adaptationsto these embodiments will be apparent to those skilled in the art andmay be made without departing from the scope or spirit of thisinvention.

1. A liquid desiccant regeneration system, comprising: a liquiddesiccant regenerator comprising an engine producing a heated exitstream, and at least one dehydrating tube comprising a first water vaporpermeable wall; a low concentration liquid desiccant stream feeding intosaid liquid desiccant regenerator; and a high concentration liquiddesiccant stream exiting said liquid desiccant regenerator, wherein acarrier stream and the low concentration liquid desiccant are in contactwith opposite sides of said first water vapor permeable wall, whereinthe low concentration liquid desiccant stream is heated by heat from theheated exit stream to drive water from the low concentration liquiddesiccant stream through the first water vapor permeable wall to thecarrier stream to form a humidified carrier stream, wherein a desiccantconcentration in said high concentration liquid desiccant stream ishigher than a desiccant concentration in said low concentration liquiddesiccant stream.
 2. The liquid desiccant regeneration system accordingto claim 1, wherein said heated exit stream is selected from the groupconsisting of heated heat exchange fluid, an exhaust stream, or both. 3.The liquid desiccant regeneration system according to claim 1, whereinthe heated exit stream is an exhaust stream and the carrier streamcomprises the exhaust stream.
 4. The liquid desiccant regenerationsystem according to claim 1, further comprising a heat exchanger,wherein the heated exit stream contacts and heats the carrier stream inthe heat exchanger.
 5. The liquid desiccant regeneration systemaccording to claim 4, wherein the carrier stream comprises ambient air,recirculated air from a space being air conditioned, or a combination ofboth.
 6. The liquid desiccant regeneration system according to claim 1,wherein the heated exit stream is heated heat exchange liquid exitingthe engine, and wherein the heated heat exchange liquid contacts andheats the low concentration liquid desiccant stream, the carrier stream,or both.
 7. The liquid desiccant regeneration system according to claim1, wherein the heated exit stream is heated heat exchange liquid exitingthe engine and a heated exhaust stream; wherein the heated heat exchangeliquid contacts and heats the low concentration liquid desiccant; andwherein (a) the heated exhaust stream contacts and heats the carrierstream, or (b) the carrier stream comprises the heated exhaust stream.8. The liquid desiccant regeneration system according to claim 1,wherein high concentration liquid desiccant stream is directed throughan air conditioning system, wherein said air conditioning systemcomprises: at least one dehumidification tube comprising a second watervapor permeable wall, wherein process air stream and the highconcentration liquid desiccant stream are in contact with opposite sidesof the second water vapor permeable wall, wherein moisture from saidprocess air stream passes through the second water vapor permeable wallto the high concentration liquid desiccant stream.
 9. The liquiddesiccant regeneration system according to claim 8, wherein said airconditioning system further comprises at least one air conditioning heatexchange tube, wherein: (a) said high concentration liquid desiccantstream and a heat exchange fluid are in contact with opposite sides ofthe air conditioning heat exchange conduits, for cooling said highconcentration liquid desiccant stream, (b) said process air and the heatexchange fluid are in contact with opposite sides of the airconditioning heat exchange conduits, for cooling said process air, or(c) said high concentration liquid desiccant stream and a first heatexchange fluid are in contact with opposite sides of a first group ofsaid air conditioning heat exchange conduits, for cooling said highconcentration liquid desiccant stream, and said process air and a secondheat exchange fluid are in contact with opposite sides of a second groupof said air conditioning heat exchange conduits, for cooling saidprocess air.
 10. The liquid desiccant regeneration system according toclaim 9, further comprising: a water recovery system, comprising: awater recovery heat exchange tube, wherein said humidified carrier airand a water recovery heat transfer fluid are in contact with oppositesides of the water recovery heat exchange conduits, a water reservoirfor receiving water precipitating from said humidified carrier air, anda flow control system for controlling transport of a water stream fromsaid water reservoir to one side of said air conditioning heat exchangeconduits.
 11. The liquid desiccant regeneration system according toclaim 8, further comprising: a high concentration liquid desiccantreservoir, having an inlet in fluid communication with an outlet of saidliquid desiccant regenerator and an outlet in fluid communication withan inlet of said air conditioning system; a low concentration liquiddesiccant reservoir, having an inlet in fluid communication with anoutlet of said air conditioning system and an outlet in fluidcommunication with an inlet of said liquid desiccant regenerator; orboth high and low concentration liquid desiccant reservoirs.
 12. Theliquid desiccant regeneration system according to claim 11, wherein (i)a capacity of said high concentration liquid desiccant reservoir issufficient to operate said air conditioning system continuously for atleast one hour, (ii) a capacity of said low concentration liquiddesiccant reservoir is sufficient to operate the liquid desiccantregenerator continuously for at least one hour, or (iii) both (i) and(ii).
 13. The liquid desiccant regeneration system according to claim12, wherein the air conditioning system consumes high concentrationliquid desiccant at the same rate that the liquid desiccant regeneratorregenerates the high concentration liquid desiccant from the from thelow concentration liquid desiccant.
 14. The liquid desiccantregeneration system according to claim 1, wherein the engine generatesenergy through electrochemical oxidation of a fuel.
 15. A method ofoperating a liquid desiccant regenerating system, comprising: providinga low concentration liquid desiccant stream; providing a liquiddesiccant regenerating system comprising: a liquid desiccant regeneratorcomprising an engine, wherein heat from said engine is used to convertsaid low concentration liquid desiccant stream to a high concentrationliquid desiccant stream, and operating said liquid desiccantregenerating system to produce the high concentration liquid desiccantstream, which has a higher desiccant concentration than the lowconcentration liquid desiccant stream.
 16. The method according to claim15, wherein said liquid desiccant regeneration system further comprises:an air conditioning system that converts the high concentration liquiddesiccant stream to a low concentration liquid desiccant stream whiledehumidifying process air supplied to an air conditioned space, andwherein said operating comprises transporting the high concentrationliquid desiccant stream to said air conditioning system, then transportsthe low concentration liquid desiccant stream from the air conditioningsystem to said liquid desiccant regenerating system.
 17. The methodaccording to claim 16, wherein said operating comprises: operating saidliquid desiccant regenerator continuously, and operating said airconditioning system intermittently.
 18. The method according to claim16, wherein said operating comprises: operating said liquid desiccantregenerator when said air conditioning system is not operating
 19. Themethod according to claim 16, wherein said operating comprises:operating said air conditioning system when said liquid desiccantregenerator is not operating.
 20. The method according to claim 15,wherein excess electricity produced when said engine is operated issupplied to an external power grid.